gccgo does support Solaris, and should support any operating system that uses ELF binaries.
The gc Go compiler currently supports FreeBSD, Linux, Mac OS X, and Windows. That's at least 95% of the servers out there (probably more). There is code to support NetBSD, OpenBSD, and Plan 9, but we have held off polishing it for Go 1.
Is it a huge amount of work to support non-ELF formats? I haven't looked at the code, but I guess it is not using bfd? AIX uses XCOFF, not ELF. I'd be interested in finding out what it would take to add support.
gccgo works without gold, albeit not as well, some people have tried it even on Irix. iant told me even Windows might work as is, though nobody tried. In any case, it should be very easy to make Windows work as well.
The gc Go compiler currently supports FreeBSD, Linux, Mac OS X, and Windows. That's at least 95% of the servers out there (probably more). There is code to support NetBSD, OpenBSD, and Plan 9, but we have held off polishing it for Go 1.