At an Asian bulletin board, is seems that the RV870 surfaced with specs and all, it supposedly comes with a 384 Bit memory interface, but that info seems shady and somewhat inaccurate, we'll leave that info as is.
Other colleagues published a 3DMark Vantage scores in the performance preset for the mainstream solution RV840 (Juniper) already a few days ago. That chip reached a P9500 points, while they did not give any further details about the test system. But this causes a ranking between HD 4850 and HD 4870.
That same source has also a result of the flagship product RV870 (Cypress) on hand. But they did not disclose exact performance number, but a range in-between P16000 and P18000, which is almost twice the RV840 and passing the HD 4870 X2.
- Cypress/RV870: P16000-P18000
- Juniper/RV840: P95xx
- Redwood/RV830: P46xx
Though 3Dmark says very little, it's safe to assume that the new flagship card will performance double opposed to the last generation.