(Wired Equivalent Privacy). WEP data encryption is defined by the 802.11 standard to prevent (i) access to the network by "intruders" using similar wireless LAN equipment and (ii) capture of wireless LAN traffic through eavesdropping. In addition to the security provided by SSID, ZoomAir incorporates WEP, allowing the administrator to define a set of respective "Keys" for each wireless network user based on a "Key String" passed through the WEP encryption algorithm. Access is denied by anyone who does not have an assigned key.
I'm guessing here but maybe it's something to do with the hotels's security policy in that you have to get a wep key from the reception desk to access the internet, as for the others? a bit lax on the security side of things, who knows