How can I add an empty directory (that contains no files) to a Git repository?
I've been facing the issue with empty directories, too. The problem with using placeholder files is that you need to create them, and delete them, if they are not necessary anymore (because later on there were added sub-directories or files. With big source trees managing these placeholder files can be cumbersome and error prone.
This is why I decided to write an open source tool which can manage the creation/deletion of such placeholder files automatically. It is written for .NET platform and runs under Mono (.NET for Linux) and Windows.
Just have a look at: http://code.google.com/p/markemptydirs