We're working very hard with chip vendors to make sure folks are getting the best experience possible running Unity in the forth-coming release of Ubuntu (Natty). Jean-Baptiste Lallement has posted to the QA mail list, asking for committed volunteers to test the nVidia drivers in Unity on a weekly basis. You can read his email here:
Jean-Baptiste links to detailed instructions in his email. The QA Tracker for this effort is here (but please be sure to read his email and follow the instructions that he links to):
We look forward to hearing from you!
Photo Credits: jackyalcine (slightly modified)