For what it's worth, you can do that with Darcs import/export. I've kept parallel git and hg repos synced that way with a cron job; it could be done with a hoo

For what it's worth, you can do that with Darcs import/export. I've kept parallel git and hg repos synced that way with a cron job; it could be done with a hook, but that slowed down pushes too much in my case. (Doing that basically assumes one branch, i.e. linear development in Darcs.)