This article appeared in Inside Higher Ed this morning. The author discusses recent studies that have suggested that collaborative learning tools (especially those that facilitate the inclusion of visual images) enhance learning for students participating in those collaborative learning experiences. Google Docs is mentioned specifically.
The other really interesting thing about the article was the mention of a new feature in Adobe software where a reader can attach sound clips to electronic documents and send them back to the author with feedback, etc. Apparently this is being used by faculty to comment on student work and seems to have a positive impact on improving their writing. I hadn't ever heard of this and thought it was pretty interesting.