While researching 802.11i, I ran accross a short summary of the various 802.11 standards and thought I'd post it for anyones reference. It from WG3 meeting in Helsinki, Finland presentation from Ericsson. It a bit dated from July of 2002 but still good overall summary.

802.11 Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)

802.11a High speed Physical Layer at the 5 GHz band.

802.11b High speed Physical Layer at the 2.4 GHz band.

802.11d Specification for operation in addtional domains.

802.11e Medium Access Control (MAC) Enhancements for Quality of Service (QoS).

802.11f Inter Access Point Protocal (IAPP) is a practice not a protocal.

802.11g Higher speed Physical Layer Extension in the 2.4 GHz band.

802.11h Spectrum and Power Management extensions in the 5 GHz band in Europe.

802.11i Specification for Enhanced Security (It was thought to be a final standard by the end of 2003 but it doesn't look like that is going to happen).