I doubt that it will have any affect on the election at all. The base that would be stirred up would never vote for a Democrat in the first place.
I'm afraid this just isn't the issue it once was. The polarization is complete on it, and the center mass off voters doesn't really consider it a huge issue, in my opinion.
The decision, either way, will slip right under most people's radar.
Degeneracy Day
I don't think your are correct. I suspect that if Bush or soem others were to step up and make it an issue - then it would be a turning point issue .... that is IF the court rules in favor of Homosexual marriage.....