Yup, more on the subject of a home-grown Twitter client. This time, posting and sorting out the UI somewhat have both been achieved:
Posting tweets is amazingly simple - just take the tweet and stuff it into the body of a POST NSURLRequest. The Twitter API even handily returns the posted tweet, so the same code which parses the friends timeline can also insert the new tweet.
So, where to go next? Well, I'm getting bored of typing my password in all the time so Keychain would be nice, @reply buttons and perhaps searching. I'm going to need cache management soon, too.