The folks at WebOS Ports have released a video of open webOS booting and running on a Samsung Galaxy Nexus today, hours after HP announced the code release. As we understand it, the device boots up and Wifi is working, but the core function of things like cellular radios, sensors, and the like aren't yet active. Nor is any soft of graphics acceleration, as you can see from the video.
I'll say this right now -- don't discount this because it looks laggy and, well, sucky. The folks behind the project have had access to the code in beta form for a while, but it tales a lot of time (and the right device) to make something like this happen. When it's ready for public consumption, even at an alpha level, I'm sure the people at WebOS Ports will be there to share and help out. In the meantime, be sure to hit up webOS Nation to keep tabs on how this one plays out.