It's too early to tell, but I'm still thinking that when it comes to first party titles, the PS3 will take the cake. The question is how long it will take for 3rd party titles to show a difference. For now the 360 has the advantage, but the question is will that ever change? Much of it will probably depend on the PC. Right now, the PC and 360 versions of games are close together, as it has been at the beginning of the previous cycle, and you see a big surge in PC/360 games. At some point in the future though, the PS3's architecture will have become more obvious and familiar, and things may change. Important in this respect may be how the UE3 turns out on the PS3. The most recent reports appear to be positive, and I think we'll find out more soon.
But you never know how these things turn out. There are still very interesting times ahead!
1st party and '2nd' party developers will stay important though, as many of the key technologies are being shared, on the PS3 for instance through Edge. The question is how fast these things will end up in 3rd party games.
One of the most important things in the next generation is a general paradigm shift in programming and development. PC style development so far has concentrated on GPUs not only because the GPU offered a lot of performance, but also because on the PC the GPU and CPU haven't been as easily tied together, and the GPU vs CPU power discrepency has been very wide for a good while in that respect. In this era where PC, PS3 and 360 are relatively close together, and each have a smallish install base, this has informed game development especially for multi-platform games. But with multi-core PCs, faster bandwidths, as well as both the 360 and PS3 being multi-core, we'll see some changes. And then the question is whether or not the PS3 has an advantage under those new circumstances.
I think the 360's graphics card is interesting and in some respects seems to be a closer decendent of the PS2's graphics card than the RSX seems to be. But the Cell does give a strong advantage. I'm willing to bet that the Havok Engine, in its optimised for Cell form, does in fact perform rather well on the Cell, who knows maybe even the 5x better that Mintmaster considers the threshold for a significant difference.
It's so hard to guess what will matter most in the end. Right now Stranglehold's rather unorthodox use of the extra space, i.e. including the full HD remastering of Hardboiled on the disc, is quite interesting.
In my view, there is a clear difference in terms of how the 360 and PS3 have been setup - the latter is much more clearly intended to last 10 years than the former (not even considering reliability issues
), and much more likely to be useful without significant hardware changes or upgrades. My experience with consoles and competition have led me to believe that this alone can matter in the end, but only if the differences become important enough.
Right now though it'll be interesting to see whether Sony will try to get EA to reach 60fps or not.