It is a cliche to say that September 11th changed the world, yet in some ways such talk is true. Russian/American relations have changed fundamentally, as Russia's quiet disappointment at America's decision to withdraw from the Anti-Ballistic Missile Treaty (ABM) shows. The surprise is that it took Osama bin Laden's terrorists to reveal that no fundamental differences of ideology, economics, or politics now exist between the two countries.
Russia experienced international terrorism long before others and thus sought joint international efforts against it long ago. Indeed, America did not lure Russia into the current war in Afghanistan; instead, Russia is using the US to rout bin Laden's terrorists and the Taliban, who caused instability across Central Asia, Chechnya, and other Russian regions.
So the new Russia/US relationship is not one of unilateral Russian concessions, as so many people here claim. It benefits both sides. With Al Qaeda and the Taliban routed, Russia's southern borders will be safer. Moreover, it is no exaggeration to say that Russian assistance - political, military, technical and intelligence - is equal in importance to the US as the support provided by its NATO allies altogether (excluding Britain).
None of this excites euphoria here. Many Russian analysts argue that once America's war against the Taliban is over, it will return to its unilateralist ways when help is no longer needed. This is a possibility. So, for today's altered Russia/US relations to flourish, two things are needed: