AMD's long awaited ATI R600 graphics chip is getting delayed and is now expected to be available in May. The card was scheduled to be released in March and would have given Nvidia's 8800 line of cards a run for their money.
According to leaked documents, the ATi card will be released in two sizes, a massive 12" long card for system integrators and a shorter 9" card for channel partners. As you can imagine, the card is going to use quite a bit of electricity, in the neighborhood of 200 to 300 watts.
No specific reason was given by AMD for the delay, but it's entirely possible that the company is tweaking drivers and finalizing hardware.