I got a very prompt mobipocket version of the book from booksonboard, except it's DRM'ed too. I don't know why I didn't expect that; a combination of my own naivety and ignorance, I guess. I had a look around the site here to find possible solutions, but a lot of them have to do with command line interfaces and some coding language which, I'm afraid, went rather sailing over my poor pointy little head. I wish I understood this stuff, but I just don't. I'm going to write back to the company and ask for my money back since I've got a book I can do nothing with.
Forearmed with a little knowledge, I had a look at fictionwise. They have 'multiformat' as I now learn the non-drm'ed stuff is known, alas the majority of what I want to buy is DRM-crippled. But at least I know some stuff is out there - I see some magazines are available in multiformat, and a good bit cheaper than they'd cost me in paper.