Check your
email for a new United promotion awarding you up to 20,000 Mileage Plus miles when you
book and fly roundtrips before March 31, 2010. This is a targeted offer, and registration is required prior to travel. Also, and this is a biggie, it appears only the higher fare buckets "H" and higher qualify. Therefore,
inexpensive seats such as K/L/T/S/W booking classes likely won't qualify (check your specific offer to be sure however).