One of the top Twitter clients for iPhone has been refreshed: Tweetie 2.1 is now available in the App Store [iTunes link]. Our friend Christina previewed the new features in 2.1 for Mashable last week, and the updated version delivers with support for Twitter lists, the Retweet capability, spam reporting, and geotagging of tweets (opt-in and optional, so don't worry that Tweetie is going to supercharge your stalkers without telling you). The full list of changes and features is on the app's iTunes page, and it's impressive.
Among the many improvements and tweaks is a crucial bug fix for an issue that had caused many 2.0 users (myself included) to gnash our teeth in frustration: the older version had a lot of problems saving state, causing old updates to appear again and, in the worst-case situation, old tweets to be sent repeatedly. It was aggravating, and it kept me from using Tweetie 2 as my full-time iPhone Twitter client -- but now it's gone.
Tweetie 2 is US$2.99, whether or not you own a copy of Tweetie 1 (it's considered a whole new app). If you're a busy Twitter user on your iPhone or iPod touch, you really ought to give it a try.