Mandriva 2009 Spring Released
Frederik writes "Mandriva just released the 2009 Spring version of its distribution. Highlights of this new version include vastly improved boot times thanks to Speedboot, KDE 4.2.2, GNOME 2.26.1, XFCE 4.6 and LXDE desktop environments, a completely rewritten Mandriva Security Centre and improved firewall and network configuration tools, OLPC Sugar environment, QT Creator development environment, Songbird audio player, ext4 support and many more. Check out the release tour and release notes for more information or immediately start downloading it."
Madriva uses rpm packages. Ubuntu uses deb packages. While ubuntu is mostly optimized for GNOME (with kubuntu being an official derivative), I THINK mandriva is mostly optimized for KDE. For major package version differences, check out here for mandriva and here for kubuntu In Mandriva you can have a root account, while in *buntu you "can't" (or, to be precise, it's strongly advised not to)
Mandriva is, IMHO, the most flexible Linux Distribution available;
Not to be rude, but there's this thing called Gentoo...