As the subject line says, the first public beta releases are now available.
A reminder to those considering taking the plunge... early beta releases can be a painful experience. Think long and hard before hitting the download button if you don't have a dedicated device for testing and you don't want to risk your device falling over at a critical time.
If you do install the beta, then make sure to file reports with Apple for each and every bug that you encounter and suggestions for anything that you think could be improved for VoiceOver, Braille, or low vision users.
The earlier a report is filed, the more likely the bug is to be fixed before the public releases later this year.