Last semester I did a big group project using Google Docs but we kept running into an issue where the spacing was different on everyone's computers. The title page would look perfect on one computer and overflow to the next page on another. This was in Chrome on OS X and Ubuntu. It really made me pine for native apps.
I recently did a small group project in which we shared a .doc on dropbox between users on Windows and Ubuntu. We had the same issue, as well as disappearing page numbers and other spooky trivia. Multi-user document editing is hand-wavy art at best.
