As MP1st suggests, this could well be an internal beta that accidentally went external: Even if the photos are accurate, Ubisoft hasn't made any announcements about an impending beta, and the game is due to hit Xbox One, PS4, PS3, Xbox 360, and PC on May 27. That said, it wouldn't be the first super-close-to-launch beta of the year.
Although Ubisoft Montral has been cultivating Watch Dogs for half a decade, the studio took the risk of delaying the game last year; it was originally due as a PS4 and Xbox One launch title. In our recent preview, Xav de Matos said, "Watch Dogs is an unbelievably slick world with unique elements and if its distractions can fit seamlessly into the narrative without feeling shoehorned in for the sake of 'another thing to do,' it may have been a risk worth taking."
Watch Dogs (03/06/2014)