It is Apple we are talking about. Upgrade early and often is the motto
Yeah, you kind of have to if you want the latest software. Then again anything beyond snow leopard is a downgrade in my book.
I'm definitely getting the new MBP at some point, I'm just waiting about a month to see whether the reviews are good and to see if manually upgrading the RAM is doable.
Main reason I'd be upgrading is because my current MBP is having a hard time keeping up with the work I'm doing, not cause I simply want the latest.
I am using the latest software. iOS 6 + Mountain Lion DP4. That said, yesterday, I caught my Mac using nearly 8GB RAM. That's half of what I've got installed, and I didn't have an IDE open.