@ kowenicki
I cant say anythign else to you.. you wont have it.. except maybe "Dont believe the hype!"
Well I studied the Cell a long time ago, a friend (one of the PS3coderz.com guys) also wrote some well written in depth articles on the subject. I have been a tech writer for various tech websites in the past. I don't just believe the "hype", I understand potential and roadblocks. That's why I said it would take lots of time and effort redesigning PC and PS2 game engines. But we have already come a long way (with regard to PS3 exclusive game engines).
If I remeber correctly back at E3 2008 Sony themselves stated that MGS4 used 80% of the PS3 potential. It's safe to say that KZ2 will be near enough to 100% of the PS3 potential.
There's a lot of untapped SPE processing potential (as for all past and even upcoming top games, including Killzone 2). MGS4 makes good use of Blu-Ray disc though to deliver high quality assets. An architecture like the PS3 takes a lot of time and effort to get the most out of it, but every step forward for your game engine is a step forward you take with you while developing your next game.
A quote will be helpful. Gears 2 will get the most out of the 360, any further future gains will be minor.