Mark Gurman, writing for 9to5mac:

Apple intends to release the upcoming iOS 8.3 as a public beta via the company’s existing AppleSeed program in mid-March, according to the sources. This release will match the third iOS 8.3 beta for developers, which is planned for release the same week. Apple then expects to debut iOS 9 at its June Worldwide Developer Conference, with a public beta release during the summer, and final release in the fall.

And:

In order to maintain a higher level of exclusivity, the public beta program for iOS will apparently be limited to 100,000 people, the sources say. Apple began seeding a select group of retail employees with iOS betas for minor releases in January. In the hands of developers since last year, iOS 8.2 will not enter public beta.

Seems like a solid idea. The more eyeballs on a release before Golden Master, the better. It will be interesting to see if Apple allows you to go back to the last public release once you have a beta installed.