WEP is already known to be broken and weak, but I see Aircrack-ptw is a new tool out that purports to break WEP (most implementations anyway) much quicker. I have not yet tried it, because BackTrack 2 decided to be a bugger about my Hermes Orinoco card and I have yet to replace it or find a solution (Whoppix and BT1 are fine with it, go figure), but once I get that squared away I plan to check this tool out. There is a paper linked on the site, and while some of it gets into some deeper mathematical (mathematical sure sounds more haughty than “math,” eh?) theory, some sections are still concise and informative (1, 5, 8, and 9).
Update: I see ISC has also been made aware of this, although they link just to the paper.