As Title "colinux related queries are off the topic?"
I'd say it is related as whole *nix system is running.
I'd vote for inclusion of cygwin (but not mingw) and Windows Services for UNIX.
colinux questions seem fine. Fedora, Debian, Ubuntu, etc. running on colinux are very similar to Fedora, Debian, Ubuntu, etc. running on a 'regular' system. Most of the questions will be the same.
I don't totally understand how coLinux works (I ran it for a few months) and I guess some of the more technical questions (Regarding the Cooperative Virtual Machine layer between the Linux kernel and the hardware) might not be a perfect fit, but this site should be good enough.
I'm willing to venture that questions about how coLinux integrates with the NT kernel would be best asked elsewhere (I'm not exactly sure where), as would many other Windows-side questions about coLinux, but of course the entire Linux userspace used would be on-topic, as would some aspects of using the kernel, and the line probably gets fuzzy in the middle there somewhere (though I expect only those at least somewhat conversant with both NT-driver- and Linux-kernel- hacking would have much to say about that part)...