He won decisively
We have finally elected someone other than a white male
He needs to be re-elected, thus his agenda will be tempered.
The overwhelming Democratic majority will give them enough leeway to really screw up by the next election.
It shows the Republican party that they cannot put up wishy-washy conservatives and expect to win.
All the focus on what is wrong with the world will be on President Obama's hands, and the media will not be able to blame the right for all of it.
And finally, the smug knowledge I will be able to look back 4 years from now and say I told you so.
In the end I agree with John McCain, President Obama really has done something remarkable and I congratulate him.
PS - I do feel a little sympathy for Hillary Clinton; all her so-called friends and supporters royally screwed her over and dumped her on what was supposed to be her crowning moment. The truth of liberal loyalty is heartbreaking when fully realized. Just ask Joe Lieberman.