Posts which are currently on the moderation queue are showing up when you visit the main forums feed. You can see the post content in the feed but when you click on the post url, you get taken to a page saying "The requested topic does not exist."

The first report of this issue appeared after the 3.0.6 to 3.0.7 upgrade. We are now on 3.0.7-PL1 (I can't confirm if it was present before that)

The only modifications we have made are to the Forums styles and very minimal at that. (Registration page and in-line ads)