Psyco is not strongly dependent on a particular OS. Precompiled binaries for Windows are contributed by users. Compiling on Linux, Mac OS/X and other Unixes should be easy.
Psyco has an emulation mode that allows it to run on other 32-bit processors but the speed benefits are not big in that case. Psyco does not support the 64-bit x86 architecture, unless you have a Python compiled in 32-bit compatibility mode. There are no plans to port Psyco to 64-bit architectures. This would be rather involved. Psyco is only being maintained, not further developed. The development efforts of the author are now focused on PyPy, which includes Psyco-like techniques. http://codespeak.net/pypy/