"I don't know if any other manufacturer has a faster lens with IS, but I suspect not."
Firstly, 50s are the easiest to make fast. Secondly, this is Canon, is it shocking that they are ahead with lens technology? No. Thirdly, this is 2012, technology is improving fast. Of course this is possible.
"When you are talking about the same framing, focal length and subject distance have equal and opposite effects, and thus they cancel each other out. When comparing lenses of different focal lengths for the same framing, DoF is determined only by aperture. So at f/2.8 for the same framing, there's no DoF difference between the 100mm Macro and the 135L, but the 135L can open up to f/2 meaning it can achieve a shallower DoF for the same framing."
Mind blown. So would this work for all lenses? Eg. a 24mm and 200mm?