This pretty much sums up what most developers, and Sony itself have said, just from different perspectives, since Sony thinks this is a positive thing:
Just when we were thinking about how long it had been since the last 360 vs. PS3 debacle, The Wheelman's Executive Producer Shaun Himmerick has come along to save the day.
When asked by ThisXboxLife.com what it had been like to develop simultaneously for Xbox 360 and PS3, Himmerick replied:
"The politically incorrect answer is that the PS3 is a huge pain in the ass. Anyone making a game, if you're going to make it for both [360 and PS3], just lead on the PS3 because if it works on the PS3 it'll work on 360."
"The easiest way to look at it is, the 360 has one big chunk of memory, but the PS3 has two chunks of memory that in total are the same size as the Xbox, but because they're split you can't share memory the same way. That will bite you in the ass, and it bit us in the ass bad."
http://www.n4g.com/dev/News-284505.aspx