There have been similar questions to this that I've been involved with before. One example: How can I get the svn revision number in PHP?
But today I'm tackling a project that is managed with BZR. I need to get the bazaar version for a particular file and publish that figure on our website in a way that it automatically updates when the file is update.
The website is all in Python so I'm open to reading files behind the scenes but I would prefer a more passive method if available.