hdtvi, the Z68 chipset will be for socket 1155, so it will be compatible with the Sandy Bridge CPUs that are currently on the market (or at least were on the market--it seems most have been pulled pending the chipset fix).
Socket 2011 will replace the current socket 1366, so that means high end CPUs. I believe the chipset for socket 2011 will be the X68.
Intel really should have released the H67, P67 and Z68 chipsets at the same time so that they could have covered the entry level, mainstream, and enthusiast portions of the market from the outset. However, considering the problems with H67 and P67 maybe the Z68 delay turned out to be a blessing in disguise.