Now we know that it’s not smooth (at all), nor does it look very usable – but it definitely is running on the device. As usual, some features like WiFi, Bluetooth and rotation isn’t working, but it’s currently in Alpha stages, and will need some time for everything to be worked out. Hopefully they find a way to fix the speeds too.
If you’re interested in giving your HTC G1 Ice Cream Sandwich, head over to XDA-developers for the files and more information. In the meantime, check out a video demonstration of it: