You have to have a college email to even register, so the vast majority of these people will be able to vote.  And if they're this excited now, just imagine what they'll be like come 2008.

In 2006, we found Facebook to be a tremendously effective organizing tool for our GOTV efforts (mostly for Jim Esch (NE-02), who ran a volunteer-driven and youth-based outsider campaign). Facebook had an "Election Pulse" feature that allowed you to show your support for a candidate. Jim got about 70% of the Facebook vote. He lost the general election with 45% of the overall vote. I don't know how well those numbers line up (there was no exit polling on the race), but there was a tremendous amount of enthusiasm for the campaign among youth, and Facebook accurately reflected that.

I think Obama's support on Facebook is a good measure of how much support he enjoys among youth. One of the reasons I support him is that I believe he will energize my generation in a way that others cannot.