No idea, the developer said he was told they were violating the terms of the Spotify API agreement by using non-standard hardware. The only thing I can think of is Spotify had/has one of their own lined up and haven't released it.

I assume this is all tied up with their campaign about unfair treatment on the App Store, but it still makes little sense to me. Apollo was written by a single developer in their spare time, it works (although not perfectly - still good given it's a 1.0 and they were working alone with no support) and has been released for almost a year.