It can do either depending on the type of glass. Some is heavily laminated like that and won't shatter (think the front windshield of a car). Others shatters entirely into pieces small enough to be relatively harmless (think the side windows of a car).
Cool, thanks for the info. I watched a recent episode of Mythbusters where they tested if a pane of glass falling from a tall building could slice a person in half, and they had to switch to an older style of glass pane, because the modern ones were designed with safety in mind.