[sphere]

I would suggest the following workflow:

Generally:
- Team XBMC creates an all-addons-Repo (lets name it ALL-REPO) on github
- add-on devs still (may) have multiple repos for multiple add-ons (github, gitbucket, svn, whatever vcs)
- add-on devs fork ALL-REPO once at github

On release or add-on update:
- add-on dev does development (in so much commits he wants) in his own repo (lets name it ADDON-REPO)
- <a script which needs to be written> will copy the ADDON-REPO's working copy into ALL-REPO/<addon> and does one commit there
- add-on dev pushes to his ALL-REPO fork and opens PR on github

regards,
sphere