Following on from ATI’s "Technology Demonstration" of a 512MB Radeon X850 XT, only for them to say "we won't actually release this", NVIDIA made their GeForce 6800 Ultra available to their board vendors in 512MB configurations. Both of these configurations are fairly high end, limiting their appeal and audience to the enthusiasts that can afford it, however recent listings from Gainward indicate movements down the line - not only do Gainward now include a 512MB 6800 GT to go alongside the 6800 Ultra (albeit it bot in "SLI" packs), but they now have an AGP 6200 512MB configuration!
http://www.beyond3d.com/
http://www.beyond3d.com/