I'm trying to get the hg-git extension working under Windows and after hours of fiddling, I finally seem to have it working. However, nothing shows up in my git repository even though the output of hg push reads:
importing Hg objects into Git
creating and sending data
github::refs/heads/master => GIT:8d946209
[command completed successfully Wed Oct 20 15:26:47 2010]
And it seems that just after I asked this, I made a trivial change. This was picked up and pushed. So it seems that you have to wait until you've made a new commit in order for hg-git to pick it up.