mkII represent a designation for a new lens in its current "configuration" which includes IS. So for the 24-70, if it does not have IS, it will be called 24-70 f2.8L II. If it does have IS it will be called 24-70mm f2.8L IS.
Hope this helps...Jacques
I see, I was under the impression that if the II was after the IS on Canon lenses referred to the IS generation instead of the a combined IS/Lens generation. Probably from an article I read on a IS II lens where they mentioned it was a second generation IS system and I (erroneously) equated that the II after the IS was a reference to the 2nd generation IS system.
Still confusing on Canons part from a end users perspective, in that if they were up to an IS IV lens and they then produced a lens that had never had IS before and marked it as just an IS, the average consumer will likely think it's an obsolete design - (IS) vs (IS IV), as canon doesn't exactly go out of their way to let you know the original release dates on their lenses.
(Hell, I've been Canon Only since 1985 and I had it wrong, chances are the average consumer will too.)