I'll be ditching the 360 after Mass Effect 3. The amount of exclusives on it that I'm interested in are in the single figures, the online 'experience' is vastly over-rated, and the difference between multiplat games is so negligible at the best of times it's barely worth mentioning.
I'm glad I got one as I've got to play games I've wanted to for a long time, but I've had my fill for now.
I meant to buy another PS3 and keep the 360 as well, but there have been so many things that have come up lately that I can't afford to do that and still have a decent game collection.