A big one here: Some new users on the site were unable to post comments. It turns out that users who hadn't entered any name information (either a first name, last name, or both) were post and get to the comment preview screen, but their comments would never actually post. There wasn't any visible error message either, making it all the more frustrating to anyone who was experiencing the problem.
The good news: It's fixed! Keep the feedback coming ... and obviously this particular bugfix will make it easier for that to happen ;)