Four -- Bazaar is heavily used, particularly in Ubuntu-related and GNU projects, and Darcs has massive user share among Haskell users.
* you're working on a project at work where the code is available via ssh at `some_host:/var/repos/the-project`.
* you're working on a project where the code is available via http from the author's site
* etc.
Currently, I think the impression they give is that you only use bzr if you're also using LaunchPad. That needs to change.
BTW, are there any other source code hosting sites that support bzr besides GNU Savannah and SF?