The core goes up to the max allowed in CCC, 700MHz. You'll need aftermarket cooling for it though.
The RAM I've been able to get up to 1125MHz. Half of my chips are running naked though.
Remember that this is in CCC, as Rivatuner and ATItool don't support these cards yet.
With RivaTuner / ATItool support core should go higher?
ATI allows for voltage control through the BIOS?