I wrote an article about installing a ROM (customized software) on the HP TouchPad. The ROM was Xron which is a variant of CyanogenMod 7 (Android 2.3). The developers, ClassicNerds, do have their own version of Android 4.0 (CM9 variant) but I have not had a chance to download and test it. However, many people are running CM9 (Android 4.0) on their HP TouchPad. For those not familiar with CyanogenMod, it is "an aftermarket firmware ... based on the open-source Android operating system. The CM team has progress in getting the OS to work. This is an Alpha 2 so there are still many bugs and some things do not work.
If you want to try CM9, webOS Nation published a nice detailed instruction guide on how to. Read carefully, do not skip steps. TabletConnect is not responsible for any damage you do to your TouchPad as the result of those instructions. They are only noted for your convenience. I will publish a detail review the the ClassicNerds' ICS ROM.