The Instant Messaging thing is just a shtick. Matthews should be comin' up.
Prediction:
Kerry will be the democrat's nominee, probably with John Edwards as his veep, and that would be strictly because of geography, trying for some southern votes. Hillary doesn't care...smart money says Bush will win re-election no matter who runs, but Kerry with his military record will make the best showing against him, and Hillary will be ready for 2008.
Running and losing against Bush won't hurt Kerry, I'm sure he figures he and Hillary can duke out the 2008 primaries when the time comes.