All the developer's that criticise the PS3 (e.g. John Carmack & Gabe Newell) come from a PC background and are used to dealing with large amounts of RAM. The X360 is pretty poor in this respect, but due to it's flexible memory architecture, it is still better than the PS3. That's one of the main reasons the PS3 (and to a lesser extent the 360) has suffered from poor PC ports (see Orange Box).
As has been typical of console system architecture in the past (with the possible exception of the Xboxes), the PS3 emphasises throughput. It has a faster processor than the 360 and faster memory; although it can't move as much data in and out of RAM at one time as the 360, it can do it faster. The PS3 is therefore much better at streaming information than the 360. Anecdotal evidence of this can be found in Burnout Paradise, which streams an open world environment and reportedly runs faster on PS3. Other examples are sure to emerge in time.
Although each system can claim superiority over the other in certain areas, the PS3 is undoubtedly a more powerful system from a technical standpoint (although that won't stop anyone arguing over the details).
While MS have tried to bridge the gap between PC and console gaming, Sony have continued along the path laid out with their previous consoles. Personally, I prefer Sony's approach, and believe that the homogenisation of PC/console gaming is a bad thing. Some games are just better on PC (e.g. FPS, RTS), while others are better on consoles (e.g. fighters, racers).
