FUD Zilla published the specifications of the Radeon HD 4870 X2 (R700) "Sparta" card and reports real volume shipments of the cards won't happen until after August 21st:
The R700 with part number 102-B50902-00 is the 2GB GDDR5 card with a 256-bit memory interface and two RV770XT chips. The card has a Crossfire interconnection via PLX chip and at the same time it comes with an external Crossfire bridge. Two cards can be connected in Crossfire X where you can get up to four GPUs to render together.
The final driver has been ready since July 25th and the reference cards have been sent almost two weeks ago, but the real volume shipment of the cards is expected after August 21st.