Apple Watch OS 2 Beta 1 now available for download

Following the WWDC 2015 keynote, Apple has published Watch OS 2.0 Beta 1 on the Apple Developer Program website. The watchOS 2 beta comes as a small download as it is a configuration profile that needs to be installed on the iPhone that the Apple Watch is paired with. This can be done either on-device or by downloading it to a Mac and then emailing it over to the iPhone in question, Apple notes.
However, those planning to install the beta, should first have their UDIDs registered with an Apple Developer Account independently of the Apple Watch they are paired with. This will require some configuration on Xcode. Assuming everything is provisioned via the configuration profile and your Apple Watch’s UDID is safe and sound on your developer account, then you're good to go.

After that, all you need to do is open the provisioning profile on an iPhone and then choosing the associated Apple Watch as the installation location. A reboot follows, with users then required to open the Apple Watch app then choose General and Software Update as they would for any normal update of watchOS.

The additional steps of adding an Apple Watch’s UDID to a developer account is obviously something that beta testers are used to, but the step of installing a configuration profile is a new one, and presumably means that all the heavy lifting is handled via iOS 9 rather than a separate download being required.