Download Facebook 3.3.1 for iPhone.

Facebook for iPhone has been updated to support Places, Groups feature, the the ability to add photos to check-ins and better tagging. The official app page has this to say about the update:
 What’s New in Version 3.3.1
1.0 Groups: share photos and posts with small groups of friends.
2.0 Deals: discover great deals around you.
3.0 Places: tag more friends after you check in, add photos.
4.0 Various bug fixes.

Follow this link to download Facebook 3.3.1 for the iPhone from the App Store.