Among those improvements is a one-touch multi-network check-in, allowing you to check in with Facebook, Twitter, Foursquare, Tumblr, and Gowalla all at once. Check-in speed is also improved, as Gowalla 3 now predicts your check-in based on your history. It also allows you to start typing your message while it acquires your location.
Gowalla has also added notes, allowing you to leave messages for future visitors, like "bring a towel," or "order the fish." You can now quickly flag places as either closed or otherwise problematic, so others don't make a trip in vain.
And of course they've added support for the iPhone 4's retina display. Gowalla is a free app, available for iOS (iPhone and iPad), Android, BlackBerry, and webOS.
source: Gowalla via BoyGeniusReport