I guess everybody has already read it, but Ubuntu has released a new release : 8.04 (8 for 2008, 4 for april). Note that this release is a LTS release (Ubuntu and Ubuntu Server only, Kubuntu and orther derivates are not ong term surpport release). As a result, you can upgrade from Ubuntu 7.10 (aka Gutsy) and 6.06.2 (aka Dapper).
I run 8.04 on my laptop and on my personal servers for several months now, and it run quite well. This bug on Ubuntu Kernel made my life at work a bit more difficult, but it should hopefully be fixed in 8.04.1 (due july 3rd).
Now, it’s time to be intrepid!