Apple has just announced a new messaging service called iMessage. The “BBM killer” is available within iOS5 for all iPhone, iPod Touch and iPad users, and it will allow you to start a conversation on one device, while continuing it on another as you see fit.

iMessages support images and videos, and everything is sent encrypted over the air. Users will be able to read receipts, type indicators and fully sync across iMessaging devices. iMessage notifications will come in like other push messages in the Notifications Center.

For a complete run-down of today’s announcements, see our post: Everything you need to know from WWDC 2011 in one handy list