Facebook today released its latest version 3.1 of its mobile iPhone app, bringing a key heavily requested feature to the device: push notifications.

iPhone users no longer have to obsessively manually refresh their Facebook app for new messages or activity. They can just let it run in the background, and get the notifications pushed to them as they happen, in almost real-time.

The Facebook 3.1 app now lets users get push notifications from Facebook messages, wall-posts, friend requests and confirmations, tags, events, and comments, with a pop-up message and a sound.

Users can now also sync their Facebook friend’s photos with their contact pictures on the iPhone address book.

You can get the latest version by simply downloading it from the iPhone app store.

The only official mobile Facebook app that offered push notifications was previously only on the BlackBerry platform.

The BlackBerry platform has, and still does have a competitive edge over other smartphones with push notifications since data is routed through the patented RIM servers. However, as technology evolves, the BlackBerry is slowly loosing its edge as devices such as the iPhone slowly catch up. More recently, Apple added Microsoft Exchange support for corporate push email on the iPhone, and the Google phones too offer push gmail via IMAP idle.