When we last left WPA (in our November 2002 WPA - Wireless Security for the rest of us NeedToKnow) it was but a gleam in the eye of the Wi-Fi Alliance and a hardy band of brave souls. They had decided to stop waiting for the IEEE Task Group i to finish its work, take a subset of the technologies the Task Group was working on and get them to market as soon as possible.
At April's Networld+Interop show in Las Vegas, the Wi-Fi Alliance proudly entire portion of its website to promoting and explaining WPA, and it's a decent resource if you need some help in wrapping your mind around this new wireless security feature-set.
A handy document there is a presentation they did for us slow-on-the-uptake Media types at last April's Networld+Interop kickoff session. It gives a summary of both the background of WPA and the elements that now go into it.
One of the simple explanatory devices they used was this equation for WPA:
WPA = 802.1X + EAP + TKIP + MIC
It pretty much wraps all the "what" of WPA into a nutshell and I'll use it to quickly review each of WPA's components.