We're hitting a point where developers have been working on the PS3 and XBox 360 for nearly 5 years and nothing has been shown for either console which is dramatically better than what the other console can produce; and the few games that people would claim give the PS3 "The Edge" are almost all games with such insane budgets that it is questionable whether they can turn a profit at all. If given enough time and money to tweak every model, texture and effect in a game to eliminate waste you can get any system (including the Wii) to do some amazing things, but it is (generally speaking) not a practical approach to game development and few developers would ever try it.
Now, from a technical perspective the PS3 will not stand up well against a next generation console ... Consider that today a (roughly) $100 graphics card, the ATi Radeon HD 4770, plays the same games as the PS3 and XBox 360 at twice the frame rate at a higher resolution with higher polygonal/texture detail, more complicated shaders, and with better AA and AF. Two years from now it is likely that a $100 graphic card will produce images with similar per-pixel detail at 1080p@60fps as the PS3 and XBox 360 could do at 480p@30fps, and a $100 graphics card represents graphics hardware which would be less expensive than what was in the PS3 or XBox 360 at launch.
