This month I got back into an x86 compiler I started last May. It lives on github.
The code is a bit of a mess but it mostly works. It generates Mach object files that are linked with gcc to produce executable binaries.
The Big Refactoring of January 2010 has come to an end and the tests pass again, even if printing is broken it prints something, and more importantly compiles test/test_huge.code into something that works.
After print is fixed I can clean up the code before implementing anything new. I wasn't sure if I'd get back into this or not and am pretty excited about it. I'm learning a lot from this project.
If you are following the Mach-O posts you might want to look at asm/machofile.rb, a library for creating Mach-O files. Using it is quite straightforward, an example is in asm/binary.rb, in the #output method.
Definitely time for bed now!