If I may get back to the point.


I think the post from Wickerprints is spot on, the reason why this lens does not have IS could be optical constraints. This lens is (for me) somewhat unusual because it is wide (24mm) when the barrel is fully extended, and narrow when retracted (makes the lens hood easy). It may not be possible to deliver an IS with the current lens configuration, which means a totally new design, which could mean years of testing.


From reading Canon Rumors (OK this is no authoritative source) there are at least 5 test 24-70 lenses in the field, with and without IS, so something may be comming.


Now let us give Canon some credit their knowledge of optics. Canon is not one of those companies who just want to sell the same product unchanged for the next 20 years. Canon is one of the great innovators in optics and engineering today, if IS is both possible and provides an advantage, then it will come.