My two cents:
I would define a socialist politics as basically anti-capitalist and democratic. This is broadly speaking, obviously. Most people I argue politics with off-list think of socialism as simply meaning a centrally planned economy. Looking from a long-term point a view, there's part of the problem. Capitalism's contradictions and fundamental flaws are simply non-existent from this point of view. There is no alternative. As time passes and the Soviet Union fades in memory, the strength or rather persuasiveness of the argument against Capitalism will grow. Even now, Jeffrey Garten's panic over the resistance to world trade as dictated by the WTO demonstrates an anti-capitalist ethic, however inarticulate. Granted, most of the public couldn't care less about trade issues, but should the stock market collapse many more will.
Many will be repoliticized, so there's one solution - if you can call it that - to the problem of pervasive apathy and cynicism. Doug, your timeline of depoliticization, from WWII to the present, highlights the fact that the last occurence of mass politicization was during a period of crisis. If there is another crisis, a socialist politics should argue that certain reforms don't go far enough and that these reforms would allow a backsliding similar to what we've witnessed during the last twenty-five years. That is, if socialists didn't spend all of their time combating fascists.
(After a crisis would be a good time to try to rewrite the Constitution - I'd keep the Bill of Rights, and add some more - in such a way as to help repoliticize the populace and limit or eliminate corporate influence. Maybe this is wishful thinking, but I think if deconstruction and postmodern anti-essentialism trickle down to the high schools and general populace, it would cause more people to view the Constitution as malleable and as just a text and not as something sacred. I know I'm being scandalous. nyeah!)
If there is no crisis, and the frog slowly continues to cook on the frying pan unawares, as they say, anti-corporate campaigns could prove fruitful. Corporations will dominate more and more and a socialist politics should highlight where government is just the handmaiden of these huge, unaccountable institutions. Part of what I liked about the film _Fight Club_ was that amidst the impotence and cynicism and apathy, the main character knew and acknowledged that corporations were running things. He sardonically noted that should we colonize outerspace, the moon would be renamed the Microsoft moon and the stars the Starbuck stars, the sun the Nike sun, etc. etc. The question becomes how do we combat corporate influence effectively.
Eric's right that campaign finance reform is a good start. I read about a business group that is campaigning for campaign finance reform b/c the members feel it will help reduce the apathy and cynicism of the citizenry. Kentucky Senator Mitch McConnell sent threatening notes to some of the CEOs involved, which they laughed off.