ah. yes, both are still available, and it seems they're gradually nudging people over to the new one, with the option to revert to the old one. Sort of like what hotmail/Live did when they launched their ajaxified interface.
At first I hated the new one, because everything moved around and it took me a few minutes to find where things had gone. That and a couple of apps I had built were broken in the new interface (grr!).
But once you get used to it, it's rather nice. Far less cluttered, especially on those profile pages where people have added piles and piles of apps.