The tale of creating a git mirror for Mozilla
ehsanakhgari.org
ehsanakhgari.org
The ideal case would be complete interoperability, where you could use git locally, yet collaborate on a daily basis with people using the project's non-git VCS, and no one would be inconvenienced -- or even necessarily aware of other developers' choice of VCS!
My impression is that this is the goal of the git "svn remote" work which has been slowly worked on for a quite a while, mostly by Google-Summer-of-Code participants.
With svn-remote support, subversion repos would be handled as a special types of remote at push/pull time, instead of requiring the user to use special commands and a different workflow. This same discipline would work for other repo types as well, and I think much of the infrastructure work being done now will be useful for implementing remote handlers for them.