That depends on the developer to be honest; BethSoft complains about the small amount of RAM on the PS3, yet none of the first party developers that know how to work the system do.
In other words, they need to stop making shitty ports from the 360.
1st party devs won't say anything bad about their console of choice....they're paid by the console maker.
PS3's inferior in memory total and in GPU. PS3 is a 256MB system with a 256MB graphics card, the OS apparently takes up more memory than the 360's OS, and the 360 also has a small amount of embedded dram (~10MB) for its gpu, pushing its total a little higher and giving it a very fast frame buffer (in addition to having a more powerful and flexible gpu).
However, the Cell processor on the PS3 is a pretty big advantage for it, but I don't think most devs use it well. Especially for cross platform ports. And since most games are cross platform, they're designed around the limitations of both systems, although the 360 advantages are easier to take advantage of (as most cross platform games have higher framerates and texture resolution on the 360), while designing a game for the Cell processor would require a redesign that would make it unable to run on the 360. Similarly, a game that really does take advantage of the 360's better memory arrangement would be hard to put on the ps3 without really stripping it down.