Some guys over at DroidNerds put a compiled AOSP version of Ice Cream Sandwich on the OG Motorola Xoom, with excellent results. They claim that the only thing not working is the camera at this point, but that the performance increase was "crazy fast" and said that, "multitasking through the applications and browsing the internet felt like we were using a whole new device." The included a video too, which you can see above. Enjoy!
Source: XoomForums via DroidNerds