We had this problem with GNU Octave.
Eventually what happened is that the lead dev got paid by a large company to provide these Windows builds. He went and forked MXE into mxe-octave. Since Octave has always been built on GNU/Linux, the easiest thing for him was to cross-compile into Windows. This has worked remarkably well, and now every interested Windows developer is working in the same way, cross-compiling. With a few tweaks, mxe-octave has actually also made it easy to build all of Octave and its dependencies without cross-compiling (i.e. targeting Linux).
Oh, and because cross-compiling into Mac OS X is impossible, we still have this problem with Mac OS X.
Mozilla is working on cross-compiling Firefox for Mac from Linux.
I think it would be great if that process could be abstracted out for others to replicate for their own software.
This is interesting. Do you know any details about this? I am mostly curious about how they handle things like the Apple frameworks at build time, which are undistributable. That was a long thread, but I didn’t see anything about doing an app bundle. It would be nice if we could have a mechanism for building one of those.
I don’t know the details very well, unfortunately. AIUI, the intended output is a .dmg with Firefox.app inside from a Linux build machine.
The key piece of it seems to be using crosstool-ng to perform Mac build steps on Linux.
Is your question about distributing the Mac SDKs, or some other Apple blob?