I was having a problem with the Network Manager in Feisty Fawn. Specifically, it was not giving me the option to use WPA as an encryption method. I've configured wpasupplicant in the past and I really didn't feel like dinking around with it if I could avoid it so kept searching. From everything I was reading and seeing during my searching for a solution, it looked like something was really borked with my configuration of Network Manager. I finally found this step by step fix to take care of the problems that I was having:

http://www.debianadmin.com/enable-wpa-wireless-access-point-in-ubuntu-linux.html

It turns out that if you have some hard set interface configs, Network Manager does not quite work the same way. Oh well, works great now.