To scan for available wireless networks in your environment, use the scan() method. It takes the network interface name as only parameter and returns an array of Net_Wifi_Cell objects.
You get an array of local wireless interfaces via the getSupportedInterfaces() method.
A cell object looks like this:
Net_Wifi_Cell {
cell => string(2) "01"
mac => string(17) "00:03:C9:44:34:2C"
ssid => string(8) "<hidden>"
mode => string(6) "master"
channel => int(1)
encryption=> bool(false)
frequency => NULL
protocol => string(13) "IEEE 802.11bg"
rate => float(54)
rates => array(12) {
0 => float(1)
1 => float(2)
2 => float(5.5)
3 => float(6)
}
rssi => string(3) "-39"
beacon => int(336)
quality => string(6) "90/100"
}