Garageband users on Laptop / iPad and iPhone can now engage in a live wireless jam if they are using a shared internet connection. The feature is called ‘Jam Session’. This has been included since version 1.2. The idea being all the users in a session can connect to a Host device which creates the session and which can also record the Jam in progress. The host device user can press a ‘Jam Session’ icon in Garageband to create a session. then other users can also press the ‘Jam Session’ button to join a session. Now devices are linked up and synced up and can start making music. You can use either Bluetooth or Wi-Fi but ALL members of the session need to be using the same for this to work. at this stage this only works for a group of people in the same vicinity using the same Wi-Fi or Bluetooth connection but maybe in the future they may implement a feature for proper Online Music Collaboration. Check out a good online tutorial here. Theres an Apple support doc re settings here, or watch this Video!