Because we've had a bad problem with spammers in the past, all posts are run through a spam filter that uses a commercial service to decide how "spammy" a post looks. If the filter doesn't like the post, it puts it in a queue for a moderator to look at and then release if the post is ok. Exactly what it looks for, I don't know. What we've seen, though, is that perfectly innocuous posts get held, more so if they include code! We're testing out a new filter module that should behave better.
If you get the "held for moderation" message, please be patient - your post will be released soon (but typically only during US west coast work hours.)
