F14 + two cards + nouveau = fail?

[DJ Delorie]

I have a setup with two GeForce 9800 GT cards, each with two monitors.
I've tried F13, F14alpha, and now F14beta and I've never gotten my
four-monitor setup to work right.

I want all four monitors in a cluster as a single desktop.

I currently use F12 with the nvidia driver and Xinerama, but rendering
performance is very slow sometimes.

With F14 the best I can do is EITHER xrandr the two monitors on the
first card and SEPARATELY xrandr the two on the second card, OR
xinerama the first monitor on each card (the second monitors clone the
first).

Has ANYONE gotten nouveau working nicely with >1 cards and >2 monitors?