Too busy getting alligators out of the Xbox360 critical-path morass to have time or effort to complete the R520 in a timely manner, including full QC and test.

"ATI code-named R520 VPU is projected to support Shader Model 3.0 and other innovations, which requires a totally new graphics architecture from ATI."

Do you really expect r520 to be a new architecture? Isnt it still based on the r3xx-r420 design?