Wirelessly posted (BlackBerry: BlackBerry8530/5.0.0.1030 Profile/MIDP-2.1 Configuration/CLDC-1.1 VendorID/417)
Based on Mileage Plus's fee schedule, it appears that non-elite members are charged hefty fees for changing or canceling award flights:
http://www.united.com/web/en-US/cont...ticketing.aspx