The HP TouchPad may have left the factory running webOS, but that hasn't stopped developers from shoe-horning Android 4.0 Ice Cream Sandwich onto it. The Cyanogen Mod team has been hard at work getting a version of Android 4.0 working on the TouchPad, and, for the most part, they have been successful.
Though important things like the camera, microphone, and hardware-accelerated video are not yet working (read: no Netflix or HD video playback for now), most everything else is. If you use your tablet to read, browse the web, and handle email as I do, then Android 4.0 Ice Cream Sandwich CM9 Alpha 6 certainly works well for that.
Performance is quite impressive, even better than many of the official Android 3.x Honeycomb tablets that I have used. Apps open swiftly and panning around the homescreens has virtually no lag. Installing CM9 on the TouchPad might not be for the faint of heart, but if you have installed a custom ROM on an Android smartphone in the past, its certainly something that you can probably handle.
CyanogenMod is a free, community built, aftermarket firmware distribution of Android OS. CyanogenMod is based on the Android Open Source Project with extra contributions from many people within the Android community (and reportedly even Google employees).