Not long ago, when wireless networking was new and rare, security was an afterthought. The reason? The scarcity of 802.11b cards acted as a form of back-handed security. If no one had an 802.11b card, outsiders couldn't very well scan your setup, right? Now, however, that's changed. Wireless gear is readily available--and cheap--so that almost anyone with a PC can afford a Wi-Fi network card, making security more vital.
Via [zdnet.com.com]