Just spotted this on the Audiobus Facebook page
This morning, Apple finished reviewing the first version of Audiobus, and it has been approved.
We’ve been working with a small group of third party developers that we already have a close connection with because we want to make sure that those apps can serve as examples for all the other developers (currently more than 400) for how to implement Audiobus.
Once our initial community of developers have finished the Audiobus integration, we’ll be all launching together and opening up the SDK to the public.
This means that we're close to having some live inter app streaming and audio routing plus processing. Audiobus has been developed by A Tasty Pixel - the folks behind Loopy - one of the more well regarded audio looping Apps.
More no doubt to come.