Noticed something new this morning down the right rail. I searched for "airline pilots", while logged into Google with location set to our west-suburban Chicago location. The ads were grouped with the following headings:
Related to airline pilot salary Related to airline pilot costume Related to airline pilot jobs
He explains that Google is essentially segmenting broad/general toward the long tail. This results in fewer page-one slots for each segment, which could make the broad match ad market more competitive, raising CPC required to appear on page one.