from what they're SAYING, the 7900GT will retail for around $299, and perform slightly better than the 7800GTX.... possibly on-par with the 7800GTX 512MB.
As for the whole 4 video cards thing, Madmatt..... it's not 4 video cards. from what i've read.... i think it's gonna be 2 dual-core video cards (like the 7800GT-Dual's that i think Gigabyte makes? not sure who makes them, but a dual core video card has been around since i think the 6800GT-ish range, but were not SLI-Capable). from what i've read, that's what NVidia is going to be pushing more towards for high-end PC's.
edit: oh, and Bman, from what i've read, the 1900XTX, for the time being, only really shows it's true colors in 3DMark's shader tests. other than that it's not much better than a 7800GTX/7800GTX 512MB.