Weird. RBL IS based on Precise... I'll take a look at Nouveau packages that I should install, perhaps it's not installing them all by default when I install kubuntu-desktop. And I will also put Firefox into the next build, as Rekonq kind of gives me some issues too when I use it on Live CDs.
I don't think installing it would make much of a difference from a Live CD...
EDIT: I read your post as "it was using nouveau and another thing that was weird"... After I reread it, I realized that you where talking about the web browser with that... It might be the card is not yet supported.