Visible Guides always have snapping behavior turned on in Illustrator. The keyboard command for toggling their visibility is shown in the View menu.
Non-SmartGuides snaps are according to cursor position. In CS4 object bounds can sense and snap to Guides as part of SmartGuides functionality, not otherwise.
Ok. When I try this my objects still snap even if I hide the guides and the only way to turn off/on the snap was to toggle "smart guides" on and off (ctrl+U).
Regards / Jimmy
Did you turn on snap to grid by accident?
Yes, but I turned it off and after that things started to act strange.