http://consumerist.com/2007/12/13/pillsbury-has-told-a/

Pillsbury has told a New York food co-op to stop using the phrase “bake-off” because they own it. Pillsbury coined the phrase back in 1949 (according to this unverifiable web source), and then trademarked it in the early 1970s (according to another). Now you know. (Thanks to Sarah!)