Popular desktop Twitter client HootSuite is now available as an iPhone application with a special '33% off' launch price of £1.19 for the first week. Unlike many other Twitter services, HootSuite lets you view statistics, lets you schedule tweets in advance – and has its own ow.ly URL shortener. It's also capable of managing multiple Twitter accounts although the iPhone app - in contrast to the desktop version – doesn't currently integrate other social networking accounts.
[HootSuite blog]