We are using the wiki feature to write the manual of a software. Each time the software gets released, we generate a tarball of the wiki. It would be greate if we could tag or create branches to support having the wiki available for multiple versions of the software.
We can do it by an external git tool or by storing the files in a repo, but the people who document the software ui are not git experts but they have no problem using the wiki. By allowing to manipulate the wiki repo through the web interface as a regular repo, many problems would be solved.