Quite frankly, the 360 isn't selling well enough for poor PS3 sales to entice developers to go 360-only; software sales for The Darkness, for example, were only double on the 360 compared to the PS3, so for a 360-only version they would've lost one-third of their sales and probably not gained that many just by optimizing a bit better for the 360 or whatever benefits they get from being exclusive.
Honestly there doesn't seem to be any safe bets for publishers right now, there's a lot of different markets and a lot of different choices for where to bring games and what types of games to make. 360 only, 360/PS3 multiplat, 360/PS3/PC multiplat, Wii only, DS only, Wii/DS multi, PSP only, DS/PSP multi, Wii/PSP multi, and don't forget all the PS2 combos -- PS2 software sales are dying off but are still competitive with the current-gen consoles.







