A good thing
"You don't see Nintendo revamping their previous generation product."
No, but it wouldn't be unprecedented; both the NES and the SNES got rebuilt in smaller form factors, and the Wii is 100% Gamecube compatible.
I think keeping the PS2 going is a good idea and it's good for developers who have already made a heavy investment in PS2 training and materials.
It sends the double message that if you invest in the PS3, Sony intends to keep their products going for years and years and years past the end of the generation cycle. Respecting developers is one of the best things you can do with the system.
Meanwhile, Microsoft has sent the message by releasing a year ahead of the cycle that if you invest in the X-Box, they're going to be more than happy to dump it and move on if they feel it suits them. That's a big caution sticker on that 360.
Speaking of living in the past, how come everyone is so crazy about PS2 emulation? We're talking about a system that almost everyone has, and if you don't have it, you can get it. It's the single best selling console of all time, and if you want to play PS2 games, guess what! You don't have to buy a $600 PS3. You can probably find a PS2 for as little as $20 used, and brand new they'll be under $100.
I'd go so far as to say that anyone that butt-hurt about the PS2 compatibility is either simply running short on reasons to hate Sony, or is simply an epic wanker.