I get the feeling that CompUSA and Frys will be raising prices soon after they find out how hot the cards are. I personally don't believe ATI is really planning on making the card $300, I think they said it to generate buzz, and hope that people will pay the extra. The original quoted MSRP was $350, and then they changed it later. If you manage to find one for $300, it's a hell of a deal, though.
My vote is that at $300-$350, the card is worth it, but if it's around $375-$400, my nod goes to the 6800GT.