Simply reading "XBOX A New Generation Revealed. Watch it live 21 May, 6pm on Xbox Live or Xbox.co.uk", it confirms the date May 21st as the date of the big reveal!
I also can't help but wonder if the fact that is just states XBOX A New Generation Revealed that this definitely may confirm the name of the console too!
Either way, mark the date in your diaries and be sure to check out SimplyGaming for all the latest once the reveal has happened!