Jumping the proverbial gun

We haven't even made it to the midterms and already folks (myself included) are yammering on about 2008. I'm not overly invested in the horse-race aspects just yet, but I did find this blurb in a post by kos interesting:

And I do know that the Change To Win unions (SEIU, UNITE-HERE, Teamsters) are really gearing up to back Edwards with all they've got making Edwards a major player in the 2008 sweepstakes.

I'm not sure what to make of this. Anyone want to shed some light on the matter with some reasoned inferences or wild speculation?