I haven't seen any threads about this yet so here it goes:
ATi has announced that two versions of the X1950 series will be released, the X1950 Crossfire and X1950XTX cards. Unlike what we've seen in the past both cards will have the same clock speeds. They will also feature 512Mb of GDDR4 memory which is speculated to be running at 2GHz, even though GDDR4 is capable of running at 3.2GHz in certain setups.
It has been confirmed that some 3rd party brands are planning on 650MHz core clocks, but some brands will probably sell cards with a higher clock speed.
And here's a link to
DailyTech's article.