One of our DB servers is being uncooperative, and we've narrowed it down to two possible problems. Both of which we're working on.
There is an added delay between when you post, and when it'll show up. Posts will show up immediately part of the time, since one of the DB servers is behind. Your posts are there, given some amount of time they will show up.
[Update: OK. The DB server looks to be caught up now. Posts should be showing up without significant delay. If you're still getting a lot of site errors, I would suggest you to come back in about half an hour.]