This change is listed as a fix – Double-clicking Zoom Tool does not set view to Actual Size (100%). (#3656264)
This is fine I guess as this makes it consistent with many other applications, but now there is no way of zooming to a 1:1 pixel ratio, is there?
Yes I'm seeing that too, unbelievable!
I've just looked at it briefly, but unless there something hidden we will be forced back to a scripted solution. This thread has .js and and AppleScripts that set the Zooming back to pre CS5 where 100% was 1:1.