Ubuntu 8.04 Hardy Heron has been out since April, but Dell wanted to do a whole bunch of testing and add support for stuff like fingerprint readers, Bluetooth, HDMI and MP3/WMA/WMV out of the box before rolling it out on their Linux systems. It's shipping on 'em as of this second. [Dell via Direct2Dell]
Awesome. I just installed this on my friends 5 year old Dell the other day. Worked beautifuly, super fast install. He's never used anything but XP, picked up Ubuntu in a day... loves the software install feature. It's a top-notch OS.
Now... Give me the upcoming Dell E with this on it! Gimme gimme gimme!