Ubuntu's rolling a custom-built default font for their next Linux release (10.10, due in October), but current Ubuntu users can preview it now. If you're an Ubuntu contributor of any sort, you might also get into a closed beta to install it.
Linux has long been criticised for its not-so-hot default typography, and Ubuntu's hired the well-known font foundry Daalton Maag to create a custom font for smooth reading on screens. Currently, anyone with an account at Launchpad (the main means of Ubuntu contribution) can check out how the font looks and help pinpoint problems with its different weights and characters. If you're an Ubuntu contributor — whether code, text or otherwise — you can also sign up to get access to a private PPA and install the font for real-world testing.
What do you think of Ubuntu's new font choice so far?