Fake. F/4 makes no sense.
Makes perfectly sense... People photogs (the only ones that need 2. would never use 11mm, because it distorts the image too much. For them, a new 16-35/2.8 is much better, which this lens would leave space for. Then Canon would have three wide angles to choose from, but to have all FL's and apertures covered, you gotta at least buy two of them...
Besides, I don't think you could do 11mm/2.8 that easy. But looks like a nice supplement for the already great lens lineup!