Many Wireless Access Point vendors include a configuration option which allows you to disable broadcasting of the SSID. Doing so does very little for your security because it only prevents the SSID from being broadcast with Probe Request and Beacon frames.
The SSID must be broadcast with Probe Response frames. In addition, the wireless access cards will broadcast the SSID in their Association and Reassociation frames. Because of this, the disabling the SSID broadcast cannot be considered a valid security tool.