Originally posted by dms I don't have/use a grip on my K20d--but a thought--to which owners with the grip may chime in on. Namely, if you put it in the freezer, would differential contraction between the grip material and the attachment metal screw (I presume) allow you to remove it (before it warms back up). If it is plastic vs. metal (screw) it seems it would get looser. In fact warming the screw with finger warmth may also help. Again this is theoretical--not based on experience with a grip.
That's often a good tactic with stuck threads, though in this case it may be less effective: the screws and tripod socket, are often made of similar stuff and of similar thickness, so they might chill and re-warm up together pretty much at the same time, but it could be worth a try. I suspect it'll work better as it starts to warm up, and I'd be concerned about condensation in the camera body, of course.
(The screw and socket themselves will both be metal, btw, )