Many organizations have resisted the installation of Wifi appliances and access points citing poor security as their primary reason. In short this is bogus... the fact of the matter is WiFi can be as secure or insecure as network admins configure it to be. In fact, in most cases people go to great lengths to configure WiFi security features such as passwords, encryption, and MAC address filters and totally ignore any such features on their standard cabled ethernet networks. One can walk in to nearly any office building plug in your lan cable and get an IP address.
Their are a host of options available to secure wireless connections (and wired for that matter) such as WPA, WPA2, WEP, and RADIUS using a variety of protocols and encryption levels. Additionally through the use of MAC address filtering and DHCP configurations a good network admin can ensure that only authorized clients can even establish a network connection.
The use of wireless networks provides enhanced security,flexibility, mobility, and usability to any home user or organization. Most of today's wifi equipment is relatively easy to set-up and configure. Also, stop relying on physical security to protect your wired connections. Implement encryption, MAC filtering, and DHCP reservations to trully protect your networks.