I’ve compiled Mercurial 1.5.4 for Python 2.6, following this guide, and uploaded it here, since I guess it’ll be useful for later:

mercurial-1.5.4.win32-py2.6.exe

I use it for Trac 0.12 in a multi-repository setting, so we can keep our old SVN repo while having some of the larger projects on Hg.