We've gotten our hands on three Z68 motherboards so far:
Asus P8Z68-V PRO
Read our review of this motherboard here.
Read our preview of this motherboard here.
The NF200 bridge chip is what makes the four x16 slots on this monster possible. They can be used in a x8/x8/x8/x8, x/16/x8/x8 or x16/x16 lane configuration. Due to their arrangement however, only three may be realistically usable.
As an aside, note that not all Z68 motherboards have onboard display outputs. Gigabyte seems to be one manufacturer so far that has created no-display models from the top to bottom of its Z68 series.
Look out for our roundup of Z68 motherboards.