Previewed at WWDC, launching in the fall.
X800 Video Card Wednesday? [Now Available]
At the time of the demo, nothing was known about the pricing or availability.
[UPDATE] The X800 XT has been announced by ATI as rumored, and will have a pricetag of $499. As this is a Retail card, it will be AGP-8X to fit with Apple's existing G5 offerings despite the wishes of many mac fans hoping that the card would accompany Powermac updates with PCI-Express. G4 Powermacs are not supported.