I am aware that the Z68/Z77 are newer chipsets, but I can see that motherboards using the P67 (B3) still support SATA3, USB3 and Sandy/Ivy Bridge CPUs. So what is the real advantage of motherboards using the Z68/Z77 chipsets compared to the P67 (B3) apart from the integrated graphics processor?
May I refer you to Wikipedia, which is frequently accurate for such purposes: http://en.wikipedia.org/wiki/LGA_1155
One thing I notice: the early chipsets didn’t support USB 3, according to that page. This makes sense, as motherboard manufacturers had to use an additional controller from companies like NEC to support USB 3.0.
As far as I can tell, that page summarizes what could be found with two or three Google searches, or two/three searches on Intel’s site.
P67/Z68 use a third party USB3 controller, whereas Z77 uses a native Intel USB3 controller.
Z68/Z77 also have Rapid Response Technology.
Z87 is the latest Intel chipset, but only supports the Haswell CPU range, it also uses a new CPU socket LGA1150, whereas P67/Z68/Z77 uses LGA 1155