Any particular reason?
> We could try moving them to bitbucket, but this also leaves the question of what to to do with our webpage hosting, which is currently on SF.
You could move your repositories to bitbucket but mirror the single repository for your webpage content to GitHub to use their hosting. (And if that repository is currently Mercurial, see git-cinnabar by Mike Hommey: https://github.com/glandium/git-cinnabar/ )
Or, it looks like bitbucket may have a similar feature: http://pages.bitbucket.org/