It's now rumored on the web that the Radeon HD 5870 X2 (dual GPU card) that should arrive in November/December will be selling under $500.  Hemlock (codename) would be slightly longer than the Radeon HD 5870 card so it is probably around 12" long.

Logic assumes that you can expect 2 versions; Radeon HD 5870 X2 and HD 5850 X2. From a leaked screenshot VRZone claims that from the CCC (control panel, you can see that the card in the machine is clocked at 725MHz core and 1GHz memory and comes with 1GB GDDR5 memories so probably this is the 5850 X2 version. Note that AMD is still finalizing on the clocks and other details so nothing is confirmed at this point of time.

I've tried to cleaup the photo's a little with photoshop to make them a t elast a little bit readable.