If somehow you have the impression that suppressing broadcast of an SSID (Service Set Identifier) brings about real security, think again.
As we know, when in range of a network, a wireless card, or Wi-Fi locator, will learn the SSID of a network, if that SSID is being broadcast by the access point. However, if the SSID is not broadcast there are tools to learn the name of the SSID.
Kismet is, perhaps, the most famous of these. Kismet is freeware that can monitor network traffic. Whenever a user connects to the network, the SSID is sent from the wireless card to the access point. At that point, Kismet will reveal the SSID name as that information is sent over the air in plain text.
To increase the frequency of users connecting, there are programs that will briefly disrupt the connection between the access point and other devices (e.g. void11 (flash presentation), wlan_jack). An owner or a user would probably not even notice that someone had kicked them off the network, instead of a simple disruption.
Thus, even when the SSID is not being broadcast, learning the SSID of a network is quite trivial.