Today at IDF HEXUS spent some time with ATI and also some Intel engineers and the information coming out is interesting.
All of the X800 cards from ATI will support Crossfire, including the X800GT and X800GTO. You will need a master card in order to run it and wait for the 2nd driver release. The launch drivers will just support X800XT and X850XT derivatives.
Another interesting move in the Crossfire situation is that Intel now have a 955X system which also supports Crossfire. It was confirmed to us by ATI that this would indeed run Crossfire. ATI would not tell us the performance gap, but as Fanny revealed on HEXUS recently, it turns out Crossfire was running on Intel long before ATI had it working on their chipsets.
HEXUS is also in a position to believe that Master/Slave cards are only going to be needed for the current line of graphics cards. R520 will not need one since it will support a Master/Slave combination on the fly. Whilst ATI would not comment on future products, surely this should be the case as no one wants loads of SKUs, right?