This is easily going in my book as a personal Family Guy favorite.
It all started with one genetically-engineered pig and Brian's query on 'when did Stewie get the time to raise one and without anyone knowing?' And then came all the universe jumping. From the future without Christianity (leading to a very, very sexy Meg) to a universe where dogs are humans and vice versa, and everything in-between. Some great, great animation and laughs pretty much the entire episode. The Disney universe, like almost everyone else has said, was definitely the highlight... even with the ending. Lots of other smaller chuckles peppered throughout... stuck in 'Japan won WWII,' 'Quahog in an ice age,' the one only with the man who gives nothing but compliments. I kinda knew when they let human Brian walk out off-screen while Brian and Stewie were talking that they were gonna have him hit by a car... I kept yelling 'Do it, do it!' until it actually happened, honestly.
This isn't false hope, is it? Family Guy is back to being the funniest show on Animation Domination? For one week of the '09-'10 season, at least for now, it is.