I'm sure you were all waiting with baited breath.. HAHAHA
On hour 48 of the non stop diarrhea, we went to the doctor. They said they believe it's ROTOVIRUS
They basically said that it could possibly last up to 14 days, and he might start vomiting at some point. But they also said that since he's been vaccinated against it, it might not be as bad, or last as long.
Anyway... think good fluffy kitten thoughts that this thing doesn't hit the rest of the household!