Sometimes it does get to 60fps. And you can tell it because the game becomes criminally smooth. But those instances are sparse.
It normally keeps at around 30fps with the occasional drop, 'cept for Adabat which is slowdown central (on both PS3 and 360 unfortunately, shame because it's really pretty).
Oh, and some HUBs chug terribly, which has to be poor coding because Empire City's is small and empty yet it gives me stuttering... and then I enter the Daytime stage which has a shitload of things going on and it runs good. lolwutpear.jpg
But yeah, the next title needs to be locked at 60fps for both high end versions. As a SOTC fan I can tolerate framedrops and such, but it really adds to the experience for this type of game.
Also good luck if you ever attempt to get those hotdogs in Eggmanland, I can attest they're controller-shattering hard.