(Update: linked to my post on frequency scaling down at the bottom).
Wow, I can't believe how many hours I've spent trying to make Linux work on this EEE 900. Our 900A seems to be okay, but ubunty karmic is completely broken with the 900, and hardy is seriously deficient. I tried eeebuntu, moblin, and I don't even remember what other distros. All failed miserably. Here's how I got Jaunty to work reliably with the VESA video driver.
The main problem is the xserver-xorg-video-intel driver, which locks up quickly after (or during) boot. For some reason, the i915 just seems to cause everybody huge headaches. And unfortunately, switching to the (slower) vesa xorg driver in many distros (such as Karmic Koala) causes it to lose video sync and be even more unfixable, since then the VTs (alt-F1, etc.) won't work.
Ubuntu Jaunty is the only thing that even comes close to working for me. It installs okay, and uses the vesa video driver, but has the standard trouble with the mind-rendingly awful netbook-launcher, which has plagued every netbook install I've ever tried. netbook-launcher sucks in a big way. It tries to be fancy by using OpenGL for visual effects, but in doing so either breaks video drivers or just eats up 100% CPU all the time.
Worse, Jaunty has a bug when turning it off that leaves you without a working window manager. System... Preferences... Switch Desktop Mode turns it off, and everything looks great, but as soon as you restart, you'll get a blank desktop with no menu bar, task bar, or gnome menus. Here's how to fix it, summarizing from the above link. (The above link also has ideas about what to do if you've already switched and are in that broken state).
To shut off netbook-launcher and get back to the normal gnome menus in Jaunty UNR, first switch to "Classic" mode from System... Preferences... Switch Desktop Mode. Everything should look great, but it'll break if you logout or restart now. To make sure the gnome menus load the next time, open System... Preferences... Startup Applications. Make sure UNR Launcher and Maximus are unchecked. Now click "Add" and create a "GNOME Panel" entry, running the command "gnome-panel" (no path needed). Add another called "GNOME Window Manager", running command "gnome-wm".
That should do it! You'll be limited to 800x600, instead of the native 1024x600, and of course the VESA video won't be as fast as a working accelerated driver would be. If that bothers you, feel free to spend a few days downloading and installing distros that'll break the machine entirely. Then reinstall Jaunty and reapply this fix, and you'll appreciate the suboptimal yet stable performance. Youtube and hulu work with flashplugin-nonfree, although not so much in HD or fullscreen modes.
Next up, enabling CPU frequency scaling to extend battery life.