It seems that a weakness in WPS has severely weakened the security of many WPA and WPA2 protected wireless networks. The WPA Pre-Shared Key and WPS PIN can be recovered in a matter of hours using a “Reaver”. Ars-Technica have a write up on how to use Reaver with Ubuntu here.
Lifehacker have a very good write up including a YouTube video (albeit a little shaky)
It seams that, while being introduced to make security simple for everyday users, WPS has in fact made users much more vulnerable…..