There are three parts to 802.1x Port Based Network Access Control: supplicant(client), authenticator (access point or router) and authentication server such as RADIUS or LDAP.

Articles:

What is 802.1x? By Joel Snyder, Network World Global Test Alliance

• http://www.nwfusion.com/research/2002/0506whatisit.html

Tutorials:

Using RADIUS For WLAN Authentication By Lisa Phifer

• http://www.wi-fiplanet.com/tutorials/article.php/3114511

Supplicant Software Support:

• Linux
  • Open Source Implementation of IEEE 802.1x
    • Open1x Support: TTLS-PAP, TTLS-CHAP, PEAP-MSCHAPv2, TTLS-MSCHAPv2, and EAP-SIM

  • http://www.open1x.org Commercial Implementation of IEEE 802.1x Meetinghouse

    • AEGIS Client (Linux) Support: Ethernet, wireless, MD5, TLS, TTLS, PEAP, LEAP

  • http://www.mtghouse.com

  Microsoft
  • Windows 2000 and XP

  • http://www.microsoft.com/windowsxp/pro/evaluation/overviews/8021x.asp Windows 98, ME, NT

  • Troubleshooting

  • http://www.oreillynet.com/pub/wlg/3026

  Apple

Authenticator Support:

• Linux

  • HostApMode

  Access Points
  • Cisco
    • 350 VXWorks 1100 IOS 1200 IOS

Authentication Server

• Linux OpenRadius

Public networks implementing 802.1x / EAP Types Supported / Source

• Wayport / Unknown / http://www.wi-fiplanet.com/news/article.php/905331

  T-Mobile / Unknown / http://wifinetnews.com/archives/002332.html