The main reason there's a difference in graphics between the consoles at the moment is that the 360 has a very similar architecture to how PC and previous generation consoles operate, simply, it has 3 processors and 2 graphics cards (also the cause of most of the overheating problems). The PS3 decided to go with a different strategy, in that there's a decent graphics card, but most of the effects, particles, shading etc. make use of the cell processor (8 cores, limited to 6). This creates a challenge for developers that want to create a game on PS3 and 360 as they have to code things very differently to make use of the PS3's hardware (which really is superior). So, sports games (Madden, NHL etc.) will inevitably be better for 360, and it will probably stay that way for some time. But games developed for the PS3 will end up looking awesome (GT5 Prologue for example).
So anyways, I'm a GT junkie at heart, so my money's gone into the PS3
