We're pretty happy with the results of the QA from our new GPU core and we are working with ATI to do some more extensive QA. If that goes well, the next step is a closed beta, and then an open beta (i.e. downloads on our web site).
It's taken a while to get to this point due to many fixes and changes under the hood. Some of these changes have to do with new ATI development tools for using GPUs (these changes will help the reliability of the code as well as solve a lot of issues donor side, such as problems with drivers) as well as new science we've put into the GPU code, to bring it up to date with what we now do on the PS3 (in fact, some features of the GPU code are not present in the latest 1.3.1 PS3 version, but we hope they will be included in a future version).
I'll keep everyone posted here as we go along. It's hard to tell how long this current QA stage will take (and a lot of it depends on whether any major bugs surface), but we're happy to see this baby go out the door, at least with its first small steps.