The main points that Lenin makes, using the word "monopoly," are (1) _inseparability_ of finance and production (in which financial sectors are hegemonic); (2) growing importance of _capital export_ (as opposed to old-fashioned "trade" or exchange of finished goods); and (3) _ever-increasing socialization_ of production (sine qua non for socialism!). In Lenin's days, "monopoly" took the form of mergers of banks with industries in the context of inter-imperialist rivalry in the world that had _already_ been fully divided by imperialists, hence the competition to _re-divide_ the world becoming necessarily violent. Today, we live in the world that is dominated by the Empire & its "Washington Consensus," so that _while (1), (2), & (3) still hold, forms that (1), (2), & (3) take have changed_. What is still true is that the era of "laissez faire" won't and can't return (today's "free trade" agreements are mainly "free investment" agreements); and that there is hardly any non-capitalist area in the world left, so further development of capitalism takes the form of the Empire & its "Washington Consensus" dissolving the barriers put up by the remnants of welfare & developmental states (residues of the Socialist & Social Democratic era). Today's imperialist violence mainly originates in attempts to manage the fallouts of the destruction of the aforementioned barriers, with the USA taking the lead & its junior partners shouldering increasing financial & military burdens to carry out the task of policing the world (fully annexing parts of the world selectively, managing the rest indirectly).
That said, the _main_ difference between Kautsky and Lenin is _not_ disagreement over "monopoly," "imperialist rivalry," etc. _but_ Kautsky's refusal to recognize that imperialism is _not_ a "policy" preferred by this or that faction of capital (for Kautsky's refusal to identify capitalism with imperialism implies a possibility of reforming capitalism so as to make it "non-violent"). Lenin wrote: "_Call it what you will, it makes no difference_. The essence of the matter is that _Kautsky detaches the politics of imperialism from its economics_, speaks of annexations as being _a policy_ 'preferred' by finance capital, and opposes to it _another bourgeois policy_ which, he alleges, is possible on this very same basis of finance capital....It follows, then, that the territorial division of the world...is compatible with a non-imperialist policy....[T]he result is _bourgeois reformism_ instead of Marxism" (emphasis mine, "Imperialism: The Highest Stage of Capitalism," pp. 156-7). Lenin, in contrast to Kautsky, argues that we _cannot_ abolish imperialism _unless_ we abolish capitalism. Lenin's key insight -- imperialism is _not_ a policy (that capital is free to adopt or not to adopt) _but_ what politically, economically, militarily, & ideologically guarantees the expanded reproduction of capitalist social relations, so it cannot be "reformed" out of existence, as long as capitalism exists -- holds, whether you call what you see "monopoly" or "big business" or "multinational enterprises." As long as capitalism lives, _it lives as imperialism_ (whether it takes the form of inter-imperialist rivalry or the hegemony of the American Empire or something else). This truth that Lenin defended from Kautsky _cannot be repeated too often_ in the era of cruise-missile liberals and laptop bombardiers.
>Does it mean anything to be a Leninist in 2001?
It basically means to be a Yoshie Furuhashi -- a keeper of indispensable theory, in a world without a Finland Station or a sealed German train to take her there. :)
Lenin wrote on "how to retreat":
***** The revolutionary parties had to complete their education. They were learning how to attack. Now they had to realise that such knowledge must be supplemented with the knowledge of how to retreat in good order. They had to realise -- and it is from bitter experience that the revolutionary class learns to realise this -- that victory is impossible unless one has learned how to attack and retreat properly. Of all the defeated opposition and revolutionary parties, the Bolsheviks effected the most orderly retreat, with the least loss to their "army", with its core best preserved, with the least significant splits (in point of depth and incurability), with the least demoralisation, and in the best condition to resume work on the broadest scale and in the most correct and energetic manner. The Bolsheviks achieved this only because they ruthlessly exposed and expelled the revolutionary phrase-mongers, those who did not wish to understand that one had to retreat, that one had to know how to retreat, and that one had absolutely to learn how to work legally in the most reactionary of parliaments, in the most reactionary of trade unions, co-operative and insurance societies and similar organisations. (Lenin, "Left-Wing Communism: an Infantile Disorder," at <http://www.marxists.org/archive/lenin/works/1920/apr/lwc/ch03.htm>) *****
On the paramount importance of the correct attitude toward one's own mistakes:
***** A political party's attitude towards its own mistakes is one of the most important and surest ways of judging how earnest the party is and how it fulfils in practice its obligations towards its class and the working people. Frankly acknowledging a mistake, ascertaining the reasons for it, analysing the conditions that have led up to it, and thrashing out the means of its rectification -- that is the hallmark of a serious party; that is how it should perform its duties, and how it should educate and train its class, and then the masses. (Lenin, "Left-Wing Communism: an Infantile Disorder," at <http://www.marxists.org/archive/lenin/works/1920/apr/lwc/ch07.htm>) *****
On the "glaring theoretical error" of applying "the yardstick of world history to practical politics" (Lenin, "Left-Wing Communism: an Infantile Disorder," at <http://www.marxists.org/archive/lenin/works/1920/apr/lwc/ch07.htm>):
***** The surest way of discrediting and damaging a new political (and not only political) idea is to reduce it to absurdity on the plea of defending it. For any truth, if "overdone" (as Dietzgen Senior put it), if exaggerated, or if carried beyond the limits of its actual applicability, can be reduced to an absurdity, and is even bound to become an absurdity under these conditions. (Lenin, "Left-Wing Communism: an Infantile Disorder," at <http://www.marxists.org/archive/lenin/works/1920/apr/lwc/ch07.htm>) *****
A good number of Marxists -- be they "Marxist-Leninists," "Autonomist-Marxists," or whatever -- sound absurd because they have _not_ learned from Lenin, because they have _not_ understood how to "retreat in good order...with the least loss to their 'army', with its core best preserved, with the least significant splits (in point of depth and incurability), with the least demoralisation, and in the best condition to resume work on the broadest scale and in the most correct and energetic manner." They have not learned how to correct mistakes &, in the process of correction, "educate and train" the working class and the masses in general. They _dogmatically_ substitute _theoretical_ truths about _capitalism as the mode of production_ for _empirical_ analyses of _current conjunctures_, which is the "surest way of discrediting and damaging" the indispensable theoretical truths and reducing them "to absurdity on the plea of defending" them, as Lenin puts it.
To sum up, there is much one can learn from Lenin, if you know how to read him. Lenin's core insights are lost on economists, workerists, dogmatists, & vulgar empiricists, in part because they have not trained themselves in the art of distilling theory from a mass of empirical facts. Theorizing is indispensable because it teaches us to see the forest, instead of simply counting the separate trees.
Yoshie