If you're new to AirPods, considering buying a pair, or just want to pick up some new tips.
Apple Announces FaceTime for iPhone 4 Video Calls
Video calling will require both parties to be using an iPhone 4. Video calls can be done with both the front and rear-facing cameras on the new device and requires Wi-Fi to work. Apple's protocol for video calling is called FaceTime and will apparently not use cellular data networks at all, thus the requirement for a Wi-Fi connection.
While describing the feature and its restriction to Wi-Fi only in 2010, Jobs said that they "need to work a little bit with carriers," presumably to make the feature available with cellular data connections in the future.