A post on Battle.net announces a weekend stress test for Overwatch. That means Blizzard plans to invote "a lot more players from our Americas and Europe gameplay regions" in for the three-day aduratijon. Anyone who's opted in for beta testing could be called up.
"The objective: help us stress test our server hardware and technology... and make a few Plays of the Game in the process."
The test starts on Friday at 9am PST / 5pm GMT and finishes on Monday November 23 at 9am / 5pm GMT but you'll know if you're in by Thursday. Blizzard are flagging accounts early to give testers the chance to download the client before testing begins.
"If you're selected to participate in this Beta Test Weekend, you'll see an Install button appear in the Overwatch tab of your Battle.net desktop app as well as an Overwatch Beta license in the YOUR GAME ACCOUNTS section of Battle.net Account Management." says Blizzard.
If you get in all 21 characters will be playable on three maps. There's no non-disclosure agreement on the action so you're free to stream and screenshot as much as you want. Good luck!