I think I managed to pack html2mobi and mobi2mobi into Windows binaries (using ActivePerl 5.8.8 build 820, PAR-Packer-588.ppd, -M flags to pp). They are available here (version 0.0.13):
html2mobi should work with html, opf and lit files. For lit files you need to have clit.exe in your path.
I did not test so much with lit files on Windows so there might be a problem with images but I assume that people who want to use the programs under Windows give me good bug reports...
All feedback and suggestions for enhancements are welcome.