(I realize I’m about a year late to the CS4 party, and this is old news for most but I just have to get this out of me.)
In Illustrator CS3, if you used Smart Guides, grabbing a shape at any part of a line and dragging it to any point on another shape’s line it would show you when you’re intersecting the other line, and it would snap against it.
With the “improved” Smart Guides in CS4, Adobe has replaced this with a new alignment system that wants to align your shape to edges and center points of other shapes at even angles, a clusterfuck of alignment guidelines popping up as you move a shape around, especially when you have a lot of other shapes in view. Used properly, this can be very useful but it comes at the expense of what you could do in CS3, a decidedly different thing altogether. And just like with the gray canvas idiocy, Adobe offers no legacy option to change this, again showing a baffling arrogance on their behalf. Apparently it’s Adobe’s way of the highway.
Now, this was originally going to be a far more damning post, but by sheer accident I figured out that if you hold down the Command (⌘) key in CS4 while moving a shape, it’ll function the way it used to in CS3. It’s ridiculous that you have to hold down an extra key to do something so fundamentally basic and useful, but at least it’s not completely gone (as I’m sure it will be in CS5, when Adobe surely will have come up with even more ways to make the simplest things harder to do).
I need a cookie.