Interesting. I bought a (march'09 macmini) to run dual monitors both at 1920x1200. So far it's doing the job quite well. Xcode included. Though I had to upgrade (max out) the ram.
This story is about my Macbook Air. In January I'd had enough of Apple and Renaissance mucking me about, so gave them another week to respond, they didn't so I filed the dispute. I also purchased a new 15 inch Macbook Pro to use in the mean time. Got it home, and it started exhibiting problems too: http://vimeo.com/2911394
Apple said to switch the power settings to "high performance" and leave them there. Basically I think this forces it to use one of the video cards and not the other. Since then it hasn't shown the problem, but the battery doesn't last as long...
