Software development is hard to predict, so don't take the below schedule as being set in stone. But here are my goals for beta releases:
July 27: Beta 1
August 3: Beta 2 (bug fixes based on feedback to Beta 1)
August 24: Beta 3
September 7: Beta 4
At some point in the early fall, version 1.0 should be ready to release to the public in the app stores. After that, the beta channel will continue to be updated with new and experimental features before these features are released in the public version. If you're a beta tester, you'll be able to have both the released version and the beta version installed on your phone at the same time.