Q:

License placement curiosities

Ruby gems have LICENSE file with the license text in each gem. Cocoa[Touch] open source frameworks (say ShareKit, StackKit, etc.) have license at the very beginning of each file (.h and .m). I am not sure about .NET or other interpreted languages (except ruby), but I'm pretty sure there are own choices at hand. I am wondering what are the reasons behind placing license into open source software source packages like this. Why not LICENSE file everywhere or at the beginning of every source file?

A:

The choices seem very different, but aren't actually. The common practice is to put a notice (boilerplate) stating the license and its short form at the beginning of every source file to (a) make the licensing terms clear explicitely and (b) make sure the license isn't left out accidentally in copying. The license notification you find at the start of a file is usually not the full license, because the full GNU license covers many pages and would bloat source files quite a lot.
The full license is included in the LICENSE file to fulfill GPL's requirement that the license is distributed with the project. It suffices to have one file per project here. The LICENSE file also fills the role of a fall-back license: If you omit the boilerplate at the start of some file, the code is still covered by the project-wide license.

