[userbinator]

It's called "active scan", and it's one of the default behaviours that I'd really like an option to disable, since (unless you hide the SSID) APs will broadcast beacon frames announcing their presence anyway.

At least for Android, someone else agrees: http://code.google.com/p/android/issues/detail?id=65890

[janinge]

For iOS you can use iPhone Configuration Utility or similar to add profiles for WiFi-networks, and set their SSIDs to be always broadcasting. That option should make it so that those names aren't included in the active scans, if it is to make any sense.