It has an array of sensors to help it avoid bumping into things including rangefinders, acoustic sensors, bump sensors and PrimeSense sensors. PrimeSense sensors are the same sensors that are in the Microsoft Kinect.
AVA is ready for applications like on your iPhone or iPad and is compatible with Android devices and the iPad. iRobot CEO Colin Angle:
If you can program an iPad, you can program a robot.
What seems most interesting is that AVA is ready for developers to create other applications that can easily be uploaded to AVA through the screen or tablet interface.
Click through for a video from PC Magazine with Colin Angle and AVA.