I read all about m3mirror, m6mirror, the -benh kernel, the radeon driver, differences in XFree versions, open firmware setting up framebuffers if vga is plugged in at boot time, kernel boot parameters to setup the external VGA, etc...
In the end I calculated the risks and figured there was a good chance I'd spend the next 2 days trying to figure it out, to no avail, and my slides would never get done.
So now I'm booted into OS X where both monitors were working immediately.
But OS X just pisses me off to no end. Everything just works in OS X hardware-wise, but it feels so. goddamn. slow. Linux flies in comparison on this laptop. I also hate the keyboard navigation, even in "full keyboard access" mode. If I hold down control-shift and arrows to select words at a time, it moves to the beginning/end of the line, not word. I can't minimize the damn software updater window. What's the point of that? Instead I have to drag it off-screen.
To be a little fair to Linux, the automatic hardware detection is getting pretty damn good on x86 lately. It's just this laptop (powerbook g4) that gives me so much grief. Well, I guess my old laptop (a dell) was a bitch too, the first time. Years later I put Linux on it and it was absolutely painless, once the software caught up with the hardware.
Starving... off to breakfast. (my 24 hour flu seems to be fully gone...)