I also agree that newer games and processors do help more with gaming when it comes to multi-cores than before. But Rhydian is right by saying that it doesn't necessarily mean better performance.
Also, now that you bring BF3, someone asked Johan Andersson (Rendering Architecton at DICE) on twitter some questions about processors and here are the answers he gave:
Q:can't you answer to hardware questions? Wonna know how positive effect 6-core cpu has over 4-core in bf3 :/
A:can't tell you, game is not done yet
Then he tried again...
Q:Well can you tell will it support 8-core bulldozer? Any plans? Please say you're considering it!
A:it is x86 so will of course run out of the box, don't know what the perf will be tough
It doesn't seem like they're giving much consideration about it threw twitter. But on the GDC, they did say something about focusing on supporting newer tecnologies and highend computers like multi-core processors and SLI/Crossfire configurations.
I'm confused now :/