Wireless adapter cards and access points for 802.11A/B/G networks are available and have become popular.
Already UNIX kernels support a vast number of different vendor products, with 802.11G drivers catching up. Unfortunately, the Wired Equivalent Privacy (WEP) used for link-layer security is inadequate for modern requirements and can be compromised easily. The successor security architecture (IEEE 802.11I) should be ready by the end of 2004. Several vendors have already started to implement the draft of this standard.
802.11-based networks are plagued by uninvited guests who either connect for free Internet access or for the purpose of sniffing with roaming adapter cards. Therefore, it is highly recommended to add IPSec (3DES/AES) on top of wireless 802.11 networks for transparent encryption, eventually accompanied by measures such as SSH or SSL. Alternative user-space crypto tunnels can be deployed, too. In addition, strong and encrypted authentication is necessary, because MAC-address-based accounting is of limited use, due to the fact that these addresses can be easily changed/spoofed and are tedious to deploy in a vast network of access points. IEEE 802.1X addresses some of these issues.
802.11 is not the only wireless technology available, just the youngest one. Microwave links, satellite links, and laser links will still be available for a long time. The use of GPRS (General Packet Radio Service) and UMTS (Universal Mobile Telecommunications System) is on the rise.