Mobility radeon's (laptop) will be among the first
Mobility chips have traditionally always been slower to release. It goes like this:
Desktop cards first
Mobile cards second
Workstation cards last
Most sources incl. donanimhaber & chinese leaks confirm what m3sSh3aD posted, the powerful 79xx series GPUs will arrive Q1 2012 at the earliest.
That's not what m3sSh3aD meant. He's guessing that they will release the entire top to bottom range in Q3/Q4 (using slightly inferior manufacturing process, but available earlier).