I was excited when I saw the Surface, as I really haven't seen a need for a tablet. But if it can run GSAK, that would definitely be something useful. However, if it's up in the 900-1000 range, then well, that's just too far out of range for me.
Clyde (the GSAK developer) has said he will not develop for any other platform (iOS, Android, Mac, etc.) So to answer Carl's question, I don't see how any other tablet would be able to run GSAK. What they could run is programs that use output from GSAK, but you'd still need a PC as that intermediate step.