There are a wealth of changes which can be made to an Ubuntu system that sit in a category that is half way between the obscure and the genuinely useful. Ubuntu Tweak is utility that exposes these options with a handy GUI.

If you are an Ubuntu user and a fan of the new Unity interface, you might be interested in a new lens in development by David Callé. The Books Lens provides a real-time search interface for e-books. It currently interfaces with Google Books, Project Gutenberg and Forgotten Books. By the time you read this, that list probably will have grown.

At the Ubuntu Devloper Summit on Monday, it was announced that Ubuntu 11.04 will ship with Unity as its default shell.  It will still focus on Gnome applications, and depend heavily on the Gnome libraries -- but the default interface will be Unity.  For those unfamiliar with Unity, it's the default shell for the Netbook Edition of Ubuntu.