In tapping Biden as his running mate, some say that Obama's choice shows a lack of confidence, or a willingness to stray from his promise of change. I think it shows that Obama realizes that he needs to bring some experience into his freshman ticket. Biden's liberal record is very close in alignment to Obama's vision, so I see no betrayal here. By picking someone from "the inside" Obama has a better chance at getting heard on Capitol Hill.
It will be very interesting now to see who McCain picks. Will he align himself with a former foe (Romney) known for his fundraising prowess, a popular moderate (Lieberman) to attract independents who've recently fallen out-of-love with McCain's sudden shift to the right, or a known conservative (such as Huckabee) to accentuate the difference between the democratic and Republican tickets. There's an interesting discussion of the contenders which includes the the Vegas odds for each choice.
The Olympics finish up on Sunday night. The Democratic Convention starts Monday night. So, we'll all still have games to watch!