Personally, I am quite happy to hear about this project, and can already think of a few uses.
I have a linux to macosx cross compiler which works fairly well (Although wishing I could get a newer version of CCTools). I have my work posted at http://nathancoulson.com/proj_cross....apple-darwin10, which wouldn't have been possible without all the other similar projects I found. (although I missed RayDonnally's work. I'll have to see what secrets he holds)
There is one thing my cross compiler cannot do, and that is code signing. On OSX, there is a tool called codesign, and unfortunately it does not look like there's a version that will work under linux (and all of my development is done in linux, then cross compiled for other platforms).
For linux to windows development, I use wine to run wixtools, and osslsigncode to sign the .exe/.dll files (I wish it also worked on .msi, but alas)
This would be amazing if it could be used as the main C Library for gcc (when building cross compilers) Currently, that is the one missing part, which has to be downloaded from apple.
I've never tried it, having only run stuff on jailbroken ithings.
Wine is not a failure but very good. With 1.4 I run all my Windows apps perfectly and can finally say goodbye to Windows. Having alike for OSX would allow people like me to leave osx.
I have made threads in the past questioning exactly why people weren't developing a os x wine.
BEING ABLE TO RUN FINAL CUT PRO 7 ON LINUX = OMG
I hope the performance is better than wine tho, but I bet it is since os x it's all bsd and bsd is unix and linux is sorta the same shit with x11 and stuff like that.