After spending a few days playing with the live CD version of Mandriva 2008.1 (RC1), I decided to install it onto my EeePC and use it as my default OS. In one word.... Wow!
Mandriva have stated that they've built their latest release to be EeePC friendly, and have they ever done a good job. All the hardware was detected correctly right from the live CD start-up and they've configured menus and GUI interfaces to scale very nicely with the small screen of the EeePC.
I've got KDE running with the Metisse environment and it's performing very nicely. Works great with the minimal hardware, too. It's wonderful to see a commercial distro of Linux built to work with the EeePC, right from the source... that is, not relying simply on community support or dedication to build and develop.
I think that, when the final release is published for public distribution, I think many people are going to find that Mandriva is the best system upgrade available for the EeePC.