Most academic researchers I know target just *nix, and rely on Cygwin to make their applications available on Windows. I have tried many of these projects and always found them too unstable for serious use when running on Cygwin.
Uwin looks like a promising alternative to Cygwin. I haven't tried it yet, but I found several comments that it is faster and more stable. However, I haven't seen any use of Uwin to support running *nix apps on Windows.
What are the social and/or technical reasons behind Uwin's lack of popularity?