The popular Twitter application Tweetie 2 for iPhone has been updated and now includes support for FourSquare. The new 2.1.1 version, which is free to current Tweetie 2 owners, also supports Vodpod and supports OS 3.2 as well.
Tweetie 2 Update for iPhone
Tweetie 2 is my favorite Twitter application for the iPhone (review is coming next week) and well worth the $2.99 price of admission.
You can download Tweetie 2 for iPhone in the iTunes App Store 
