If you like living on the bleeding edge, you should join the NewsBlur iOS beta program. You’ll get access to the latest releases a few weeks before they go out publicly.
All you need to do is add your email address to this form: https://docs.google.com/forms/d/1XSerwoY-PEJ7JfglNr0zOKpsoMXqplSomdORSDsZ3_g/viewform?usp=send_form
You might be wondering why this is a bit different than the older method used in the past. The old beta program used an enterprise distribution provision profile, which was available as a workaround to install apps on devices without having to go through the App Store. Unfortunately that program has ended and Apple now recommends using their new TestFlight beta program.
In order to use TestFlight, email addresses of interested beta testers need to be collected. But the benefit is that you can now easily move between beta and release versions. You will also automatically upgrade to the release version when it comes out. You can also give feedback in a more accurate way, with your device and OS version automatically added to anything you write as feedback.
So if you want to try out the latest betas, specifically for iOS 9 and a whole bundle of new features, then add your email to that list and watch your inbox. It can take up to a couple days for these emails to be imported, so be patient.