WPS makes stealing the WPA PSK as trivially easy as WEP. Basically, WPS protects the WPA key with a 7-digit PIN - cracking that PIN is enough to authenticate with the router and have it provide the encryption key.
It seems like this should be easy to defend against, but everything I've ever read about WPS says no one seems to be putting any such protections in place.
http://en.wikipedia.org/wiki/Wi-Fi_Protected_Setup#Brute-for...