This is the Hg-Git plugin for Mercurial, adding the ability to push to
and pull from a Git server repository from Mercurial.  This means you
can collaborate on Git based projects from Mercurial, or use a Git
server as a collaboration point for a team with developers using both
Git and Mercurial.

Warning, this software is still beta.  It is basically feature complete
and pretty stable now, but there are still some edge cases that aren't
handled well yet and it may be slow in some circumstances.  The user
interface is also still subject to change.