"the last update was the July release."

When you design, you design for the future. Your program should not care the frequency of the releases, but rather the sequence of the releases. Make the release named something like "July release" is not a good idea. You don't want to modify your code just because the frenquency changed.

The other thing is where to get the files to tar? If you are not using any version control system, go get one; if you do use one, get whatever you want to tar from version control system, not certain directory or anything like this.