I'm glad when something puts pressure on any government to stay honest. It's a matter of politics at this point between countries and you'd better be damned sure that Russia's not just going to let this slip through their fingers. It's a smart move on their part, free positive exposure while the U.S. tarnishes itself a bit in the eyes of many. Plus, Russia has set it up in such a way that they have the freedom to change their minds if they wish (say, within the next 3 years).

They may also be able to get some concessions or use Snowden as a bargaining chip with the U.S. down the road or it may prove useful just to keep him around. Maybe they just don't care all that much and get the benefit of a tiny publicity boost with the outside world by looking like they're more "free" than the U.S; in whatever way you slice it they get something out of it for cheap coin. When the country with the most powerful military in the world has a phrase like "We always get our man" doesn't get their man, it carries a statement that Russia wants to promulgate.