So I backed up my OS X install (using the very nice Super Duper) and took the plunge. I had a plan. It had a lot of steps.
Step 1, install the OS. No problems here.
Step 2, set up wifi. Uh oh.
There are some very clear and simple instructions on how to get Ubuntu talking to the nasty, proprietary little wifi card inside the powerbook (thanks nickm!). I followed these, and was able to scan for networks. Alas, I wasn't able to actually connect to any of them.
It appears that other people have had this problem. Unfortunately, hours of search left me without solution or diagnosis. No one has replied to my forum post. The people on #ubuntu got me to try all the obvious things (I'd already tried them), and the people on #ubuntu-au did much the same, except they were more friendly and had longer attention spans. The aussies also gave me a lead -- apparently cafuego has bundled some firmware and I should try that.
Unfortunately, by the time I got that lead, I had already begun to restore my OS X installation to its natural home.
I'm a little disappointed about the whole experience. Apart from taking up a slab of free time that I could have spent on other things,
it means I still lack a Linux workstation...
... which could be embarrassing when I'm at LCA 2007. I've registered and booked my tickets. I'm not sure if I've paid yet. They wouldn't let me pay when I registered. Hmmm. I should talk to someone about that.
Anyway, it's my intention to be in Sydney for LCA 2007. I hope to see you there, dear reader.