Blizzard games are not designed for console and you can see when playing them that significant changes would be required for them to work on console.
Valve has been making fps like a dozen other companies but somehow they don't bring their games to some console while their competitors manage it ( IW, Guerilla, ...) and then they give bs excuses of why they do not...
And please stop comparing both, Blizzard is a much bigger company/successfull company than Valve...
Wow alone is probably worth 4-5 times what the whole Valve company is worth.....
Personnaly I don't really care and were they to start developing for the PS3 I woudn't buy their shit anyway. There are enough other developers that make good enough games...( lets not forget than for all the noise Left4 Dead got, it got outsold handilly by CoD:WaW on the 360..)