Now according to them it isn't perfect yet and the touch screen is not working yet (ouch - after all isn't that the most important part of your smart phone these days...). But don't worry since this customized Ubuntu won't replace the current anderiod OS on the Nexus S. So if anything goes wrong or you don't like it then just simply remove it.
Wi-Fi and 3G seems to be working at the moment. And if you're using the older Nexus One then you will have to use or build your own Kernel package at the moment otherwise it won't work since it is only for the "S" at the moment.
For downloading and other discussions concerning this Linux on Nexus S please click here for the xda forum.