iOS 4, previously known as iPhone OS 4, will also support Bluetooth keyboards, organizing apps in folders, Home screen wallpapers, and more.
The upgrade doesn’t support the original iPhone, and some features, such as multi-tasking require at least an iPhone 3GS or a third generation iPod touch. iOS 4 will be available for the iPad later this year.
For tips on preparing for the upgrade, check out TMO’s iOS 4 Upgrade Guide, and our Quick Tip on checking to see if the update is available.
iOS 4 will be available as a free upgrade.