iMessage works with any iOS 5-capable device, sending anything an SMS or MMS can--text, photos, video, contact cards, or map locations. The feature allows iPhone users to talk to iPad users, iPad users to send video to iPod touch users, and so on. You won't be able to use iMessage to contact people with Android devices or BlackBerry phones--that's still the province of text messaging.

iMessage is easy to set up and use: All you need is an Apple ID, and you can start messaging your fellow iOS device users.

To start using iMessage, open the Settings app and tap the Messages menu. You're prompted to enter your Apple ID--that's the email address you use for buying apps in iTunes and logging in to iCloud. If you don't have one, you'll be prompted to create an account.

If you're setting up iMessage on your iPhone, people who know your mobile number will always be able to use it to message you; you can also supply iMessage with an email address where other iOS device users can reach you. If you're using an iPod touch or iPad, you can message people only by email address, so you'll have to supply one during the setup. You can use any email address you own--such as your iCloud or Gmail account.