I have lots of undergraduate notes in PDF form on my web pages (http://shef.ac.uk/nps). No one has ever asked me for the source files. Nonetheless, I have thought about releasing them explicitly in LaTeX form under a creative commons license. This has not happened for fairly mundane reasons:
Some of the notes are partially based on earlier notes by colleagues, and I have not discussed things with them.
Most courses have a fairly elaborate setup with separate files for notes, problem sheets and lecture slides, auxiliary files that are \included in the main files, Maple worksheets used to generate jpeg diagrams and so on. I have not worked out a good way to package everything.
All my courses have detailed solutions to all the problems, which I release to students a week or so after the problems have been assigned. I have not decided what would be the best thing to do with such solutions if I were to make the source files freely available. At the moment I have things set up so that the solutions are in the same files as the problems, with LaTeX macros etc to switch them on and off.