The new update keeps Tweetie’s Foursquare integration, which was first introduced in version 2.1.1 in March. Foursquare checkin tweets from your friends show a small purple icon to indicate they’re from Foursquare. When you open the tweet, you’ll see the location pinpointed on a map. Clicking that map will take you to a detailed Google map, showing you the exact location of the venue.
If you click the 4sq.com link, you’ll be taken to a venue page within Twitter for iPhone that shows the venue’s address, Twitter link (of course), and mayor. You can click the phone number to dial it directly on the iPhone. Clicking “Open in Foursquare” will take you directly to the venue in Foursquare’s iPhone app.