I reported a while ago that I was forced to tag the current state of the DTCoreText master repository as 1.0.0. The reason for this was that CocoaPods was starting to gain lots of momentum and several people wanted to use DTCoreText via a podspec.
You can have podspecs point to the master branch as well, but then you never really know what you get. This can possibly cause many headaches especially in larger projects where you cannot track the state of each individual sub-project.
Therefore it is generally recommended – if not required – to make use of tags in GitHub.