The Eclipse Mylyn (http://eclipse.org/mylyn) project started out as a university research project before it came under the eclipse.org umbrella. Furthermore, It became so successful that a company was launched around its work, Tasktop (http://www.tasktop.com).

Git does have commit metadata... and for awhile now... see git-notes... http://www.kernel.org/pub/software/scm/git/docs/git-notes.html http://progit.org/2010/08/25/notes.html