Today Dell will start shipping three systems with Ubuntu 7.04 pre-installed in the U.S.

You can choose between a Dell XPS 410n desktop PC, a Dimension E520n desktop and the Inspiron E1505n notebook.

Hardware support will come from Dell. Beyond that, users can turn to the Linux section of the Dell Community Forum for help. If you need support you can purchase fee-based options for operating system support through Canonical, including 30-day Get Started, One-year Basic and One-year Standard.
The whole Ubuntu Dell thing is a user suggested idea and Dell picked it up. This is of course great for Ubuntu and its founder Mark Shuttleworth.

The Dell site is not offering the Ubuntu systems yet. The Ubuntu teaser site is still not updated.
Via the Dell Blog.

About Ubuntu
Ubuntu is a community developed and supported project. Since its launch in October 2004, Ubuntu has become one of the most highly regarded Linux distributions with millions of users around the world. Canonical, the commercial sponsor of Ubuntu, is a global organization headquartered in Europe committed to the development, distribution and support of open source software products and communities. See also the Ubuntu site.