I don't know what Twitter's business model is, but when there's an application that capitalizes on the fact that Twitter is constantly down (join the FriendFeed Twitter downtime prediction thread if you feel psychic today), it's worrying.
Twiddict - short for Twitter addict - is a service that lets you tweet even when Twitter is down. Twiddict will constantly ping the Twitter API to see if the service is up again (practice usually known as hammering; hopefully they're careful not to send those requests too often), and send your messages as soon as Twitter resumes normal operation.
What can I say? It's both a blessing and a curse; before, us twiddicts could at least take a break when Twitter was down; this new service is just another way to push us further down into the neverending spiral of Twitter addiction.