Ubuntu has a convention of naming each release after an animal, alphabetically. 9.04 was “Jaunty Jackalope”, 9.10 was “Karmic Koala” and 10.4 is “Lucid Lynx”.
Let me say first: 10.4 is in beta at this time, with patches and updates rolling out regularly. They’ve gone into feature freeze and are focused on bug fixes at this time.
But off the bat, my comments just a day or two ago about how Ubuntu still looked like a Linux lost a lot of their weight with 10.4. The anonymous gray dialogs, like the “authorize this activity” still need polish, but the desktop itself has begun to look sexy.