It's not in voluntary travels that Hardt & Negri see a revolutionary potential, however, and rightly so, in that I don't see much revolutionary potential in increased tourism & study abroad either. They emphasize, instead, the mass migrations of illegals & other laborers, manual or mental, in general:
***** The constitution of the multitude appears first as a spatial movement that constitutes the multitude in limitless place. The mobility of commodities, and thus of that special commodity that is labor-power, has been presented by capitalism ever since its birth as _the fundamental condition of accumulation_. The kinds of movement of individuals, groups, and populations that we find today in Empire, however, cannot be completely subjugated to the laws of capitalist accumulation -- at every moment they overflow and shatter the bounds of measure. The movements of the multitude designate new spaces, and its journeys establish new residences. _Autonomous_ movement is what defines the place proper to the multitude. Increasingly less will _passports or legal documents_ be able to regulate our movements across borders. A new geography is established by the multitude as the productive flows of bodies define new rivers and ports....
...These movements often cost _terrible suffering_, but there is also in them _a desire of liberation_ that is not satiated except by reappropriating new spaces, around which are constructed new freedoms. Everywhere these movements arrive, and all along their paths they determine new forms of life and cooperation -- everywhere they create that wealth that parasitic postmodern capitalism would otherwise not know how to suck out of the blood of the proletariat, because increasingly today production takes place in movement and cooperation, in exodus and community. _Is it possible to imagine U.S. agriculture and service industries without Mexican migrant labor, or Arab oil without Palestinians and Pakistanis?_ Moreover, where would the great innovative sectors of immaterial production, from design to fashion, and from electronics to science in Europe, the United States, and Asia, be without _the "illegal labor" of the great masses, mobilized toward the radiant horizons of capitalist wealth and freedom_? Mass migrations have become necessary for production. Every path is forged, mapped, and traveled. It seems that _the more intensely each is traveled and the more suffering is deposited there, the more each path becomes productive_. These paths are what brings the "earthly city" out of the cloud and confusion that Empire casts over it. This is how the multitude gains _the power to affirm its autonomy_, traveling and expressing itself through an apparatus of widespread, transversal territorial reappropriation.
(emphasis mine, Michael Hardt & Antonio Negri, _Empire_, Cambridge, MA: Harvard UP, 2000, pp. 396-398) *****
_Despite_ the fact that mass migrations (unlike voluntary travels) are mainly results of economic desperation and/or political persecution, often costing "terrible suffering," such movements, _for Hardt & Negri_, are _autonomous_ movements, with many migrants defying the demands for passports or legal documents, expressing "a desire of liberation that is not satiated except by reappropriating new spaces, around which are constructed new freedoms" (397). Unlike you, Hardt & Negri are saying simply that we should see a revolutionary silver lining under increased suffering.
Yoshie