Apple on Thursday launched public betas for iOS 9 and OS X El Capitan. Apple has been releasing developer betas of the software since WWDC in June, and this afternoon it added the updates to its public beta testing program.
Folks interested in trying out the betas can sign up via Apple's Beta Software Program portal. Once you're signed up, you'll be asked to register your devices and install beta configuration profiles, and then you can download the betas.