Also, x86 PC GEM itself is now GPL open-source:
http://www.deltasoft.com/Default.htm
(The FreeGEM community is where I first "met" CCmper Gene Buckle.)
There have been efforts to bring across some of the Atari
improvements, but development largely stalled quite a few years ago.
On the Atari side, various people wrote replacements of various bits
of TOS - the VDI, the AES, the desktop and so on - and some of these
parts were FOSS.
Eventually, the result was a complete FOSS Atari OS, containing almost
no original Atari code but highly compatible. It's called AFROS and it
runs best on an emulator called ARANYM, which is designed for running
TOS and TOS apps on PCs, rather than games.
http://aranym.org/
Now that is seriously interesting!? I knew there was a reason I was
keeping up with this thread!