Snapping to guides and objects is the most used feature in Adobe Illustrator. The first thing you’ll notice in Illustrator CS4 and Illustrator CS5 is that it doesn’t snap to anchors and paths any more. No matter if you have Smart Guides on or off. No matter how you zoom in or out.
All kinds of virtual guides are popping up, snapping to all possible kinds of edges and anchor points of objects, under different corners. However, snapping chaos is not what you need. You just want the anchor points to snap like they used to, but they just don’t seem magnetic any more.
I could now start a lengthy rant about Adobe being lame for annoying experienced users by changing worn-in methods with every update of their creative suite for no apparent reason at all, but let’s not go there, OK?
The solution is simple once you know it: Just press the CMD-key while dragging an anchor point to another to make it snap. Despite a Smart Guides panel in the illustrator Preferences, there is no way to turn snapping on permanently.