I'll investigate a bit further. All places I've seen selling the MicroAmigaONE online state they have none for sale and are waiting for another batch...
To be really honest, I'm still amazed at the Amiga community considering the circumstances. Most people would have thought that, by now, the Amiga was a long forgotten article in Wikipedia. But alas, look at the response I had to my post! I've seen much worse elsewhere...
As for the joint project, who knows?
Thanks for the pointers. A cross-compiler is nice, but you can't run the code on the PC. You still need AmigaOS 4 running on something to debug and test. Plus, you don't seem to have access to the OS' libs, only basic shell I/O.
As for the board, let's hope I can get one soon. I don't speak german (only english, french and portuguese), but I have been to the amiga-news.de forum with the help of Babelfish. I found only a couple of uA1s already sold this year (and a few people asking for someone to sell an AmigaONE!).