The 802.11 standards groups have full plates and they will struggle to ensure that all their efforts interoperate: The development of 802.11e, the quality of service mechanism, seems to be the trickiest and will require repeated upgrades.
Problems are already surfacing. Vendors are adding their own bells and whistles, like higher speed offerings, as a way to differentiate or to speed up the upgrade process. Those extras create interoperability problems.
Even without the extras, vendors struggle to comply with the standards. Frank Hanzlik, the managing director of the Wi-Fi Alliance, told me recently that about one quarter of all 802.11b products--the most mature of the standards--submitted for approval fail certification initially. Products going through certification of the newer standard fail at an even higher rate.