Not a lot, just Ivybridge unlocked with 2 extra cores. Had my 3960X since launch though and sold it already, so will be putting one in.
Just FYI it's not really worth upgrading your cpu for games unless you're running tri/quad SLI and at a sizable resolution. Although you would notice a few extra frames with an i7 at an extra 600mhz. 4Ghz is fairly tame. I noticed my 3960x at the stock turbo 3.9Ghz was a bottleneck for me.