In case you don't know, the new Ubuntu font which is supposed to be shipped with Ubuntu 10.10 is only available in a private PPA for now.
A while back we posted about getting the official Ubuntu font by joining the Kubuntu-users group. There were way too many people joining this group so it was revoked access to the private PPA. In a discussion with Paul Sladen, he pointed to a new way regular users can get access to the Ubuntu Font Family private PPA: go to https://launchpad.net/~ubuntu-typeface-interest and click "Join this team" (you'll of course need a Launchpad account). You should receive an email when you have been accepted to this team (it will take a while - I'm not sure how long). When this happens, do not install the deb! Add the PPA so you can stay up to date with the latest versions of the font!
Important: only join this group if you are willing to provide genuine feedback or need to work on a project like making a video for Ubuntu 10.10! Also: most people will be accepted into this group. However, if you have just created a Launchpad account and/or have 0 Launchpad karma, it might take a while until you're accepted.
Paul also mentioned a bug about the leaked Ubuntu font (not the font in the private PPA) which caused a lot of trouble for both the Ubuntu and Chromium developers: the font causes Chromium to segfault. Again: that is the unofficial, very old ripped off font and not the official one in the private PPA we are writing about! If you are using that font you should uninstall it as it is very buggy.
For more info, see this: https://wiki.ubuntu.com/Ubuntu%20Font%20Family#Howto and our old post on the Ubuntu Font Family - it includes screenshots and info on what to do once you've got access to the Ubuntu Font private PPA.
Instructions and Rationale: http://design.canonical.com/2010/07/the-ubuntu-font/
Found a bug? Report it here: https://bugs.launchpad.net/ubuntu-font-family
Update: you can now install the Ubuntu Font Family from a public PPA.