I have posting from the board disabled and get a lot of posts waiting for manual insertion. If I had to find a pattern I woud say majority of these posts were cross-posts to groups not present on my board (as in reply to message nr 11111 in rec.group.whatever, which I have and 22222 in alt.group.whatever which I don't). But (there's always but) many many times first and a number of cross-posted follow ups appear in vB and then next one just gets stopped. Some posts are kept on hold simply because first message in the thread wasn't fetched, although message is available on the server and if I reset the counter it will fetch it when forced.

Another bug would be mixup of posts from time to time - I had plenty of moments when full threads and replies to another group were inserted into different thread in different board. This is minor though.

Strangely enough everything worked perfect untill last versions for 2.0 betas (ones with all changes in the code)...
For the last five days I've been purgiung all posts from one of the groups and changing servers, suspecting there might be something weird about INN we have in the office, but pulling from private account and from public server also had the issues described above...

vBulletin 2.0.1 + Usenet hack 20010528