To answer your last part:
I believe they have been posted before on this very thread and I'm not sure what the source was (they are not mine). Source was Extremetech.com, but it has been taken down.
That CrossFireX sideport is probably part of the trick, a dutch site has also stated that the PLX chip will be gone, or at least it's a different (smaller footprint/package) chip. That's because the R700 card is smaller than R680.
Also remember that the Ringbus memory controller is gone now and some sort of a hub has taken it's place.
EDIT: fixed...
EDIT2: for whatever it's worth for some, here is the official announcement of ASUS' 1GB 4850.
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