When posting from the admin interface, failures (say due to a bad password) aren't passed back up the chain. The return for do_tweet isn't checked, and the admin page isn't configured to display failures.
Currently on the "nice to have" list for the 1.0 release. It does check this in the sidebar posting interface.
If you post a tweet through the WP interface it would be nice to immediately reflect that tweet.
The tweet has to come in from Twitter to get the info they add. An immediate check can fail because of race conditions. I guess I could artificially set the last update to check in 2 min or something.
Deleting a tweet doesn't delete it on the WP side, even after updating.
Hmm, not sure if there's a good way to handle this. Likely that's just how it will work.