That being said, at risk of sounding like the skunk at the garden party (or the Lowell Weicker of the Townhall blog), it strikes me that too much GOP congratulation is a mistake.
After all, if a Republican couldn't win a run-off election in Georgia (and when Barack Obama has largely declined to campaign for him), wouldn't that be more of a sign of political cataclysm than the opposite being a sign of impending victories? That's not to say that Obama is necessarily electoral teflon, of course. When one looks at the conjunction of factors that came together in his favor this election season -- including an unpopular president who declined to defend himself and an almost-unprecedented economic meltdown -- it would have been more of a sign of a political cataclysm for the Democrats if he hadn't won than a great victory because he did.
What will be interesting is what happens if and when Obama hits the campaign trail in 2010. It's fair to say that he will probably be able to count on a core base of support for himself no matter what he does; the question is whether he will be able to rally those same supporters by his campaigning when he himself isn't on the ticket.