YouTube thinks they can take the title, and to make things more interesting they're also allowing their Facebook fans to choose which nonprofit's videos the site will feature on its homepage at the end of the race.
With 14 days left to go in a 60-day Facebook fan-off, YouTube has gained more than half a million new fans so far but has even farther to go to reach the top spot, having dropped from #12 to #16 thanks to faster growth from some others near the top. Google's popular video-sharing site apparently faces still competition from Michael Jackson, Barack Obama, Vin Diesel, and Facebook itself, not to mention pizza and, well, sleep.
YouTube appears to be a good sport though, and regardless of their position at the end of the campaign on September 28 they'll be featuring a nonprofit organization on their homepage that day. If you become a fan of YouTube you can use the poll in the left-hand sidebar to vote on which organization should be featured.