The IS has nothing to do with stills. Looks like another "video lens." Oh well, if it's better than all the current 50's, I'll get it.
IS also is very applicable for still photography.
A number of us have written that in our posts on this thread (pls read page 1).
While I've taken thousands of photos on tripods, I've taken hundreds of thousands of photos without a tripod, and believe me - in many situations using, bringing or even having a tripod (or monopod) just isn't practical (or allowed in some scenarios).
Many professional photographers use IS to get shots they otherwise couldn't have. I'm not a pro, (though plenty of my photographs have been sold) - and my photographic technique does at times benefit from IS.
Sighhhhhhhhhh. No, I meant that that's WHY Canon made this lens. Same thing for the 24-70 f/4 IS lens. Clearly aimed toward video more so than stills photographers.