I've seen some odd things recently with disappearing posts, however they are not my posts. I get e-mail notifications for the threads I subscribe to and it seems like 3-4 times in the last week I've gone to the new post and the post I got from the e-mail is not there. I know that it is possible that the person simply deleted the post right away, but it seems unlikely given the nature of the posts.
Here's an example:
BlueCC just posted a message that would have been post #318, but as soon as I went there it was gone.
Also in this thread:
kahuna posted what would have been post #67 on 11/11/08. When I clicked to go to that message it was gone.
Like I said, probably just users deleting posts, but still a head scratcher.