Pingback/TrackBack for Git?

Wouldn't it be cool if Pingback/Trackback (nice comparison here) could be implemented for the distributed VCS Git? As every object in Git is verified by its hash, security would be built-in, and new commits on top of the origin's master branch have to be verified by the user, anyway.

I'd see the following benefits of having something like Pingback/Trackback in Git:

• Automatic mirror discovery to download objects from
• Upstream author has a nice overview of available branches/forks
• Stale repositories could link to recently updated repositories
  

There are no real dangers, as there could be some checks if the pinging repository is based on the pinged repository, etc.. Content would also be protected by cryptographic hashes, so using a mirror list to pull lots of objects should be no security threat, but remove some load from the servers.

I realize this could probably only implemented with gitserve repositories (i.e. git://) and ssh+git repositores, but not with "dumb" (i.e. http://) repositories, but maybe it'd be possible to add some kind of CGI (think: gitweb) addition to allow for pingbacks. If a repository stores the URL of the gitweb installation of this repository and gitweb is extended to allow saving of ping/track-back repository URLs, we could have ping/track-back for all our Git repositories.