Over at Jeremy's blog is a blogpost about a Dell email, in which they announce the models on which Ubuntu will be offered:
We will be launching a Linux based OS (Ubuntu) on the E520, 1505 and XPS 410 starting next Thursday, 5/24. We expect these systems to be less than 1% of our OS mix for the entire year which is ~20,000 systems annually. Please cover the huddle deck below with your team by EOB Sunday. If any questions come up, please let me know so I can address them before launch.
The goal of launching Linux is to continue to give our customers more choices to customize their new Dell. Providing more options to our Linux Enthusiast customer group will hopefully create even more Raving Fans!!
Here are the links to the Dell models mentioned above:
Dell Dimension E520 desktop
Dell Inspiron 1505 laptop
XPS 410 desktop