Following last week's YouTube unveil, the CyanogenMod team has released an Alpha 0 build of CyanogenMod 9 for HP'sTouchPad, along with the complete source code for the project. As with most alpha builds, there's a waiting list of issues to be resolved, with the camera, audio, microphone, and hardware-accelerated video currently topping the bill. There are also problems with Market access as well as hardware issues carried over from CM7.
That said, the team has done a fantastic job with the port in such a short space of time, with almost everything else functioning as normal. So if you don't mind the risks involved with an experimental build, you can head over to the RootzWikifor guidance on updating your TouchPad to Android 4.