Correct! The high CPE at Denver is the reason many airlines have given for limiting/not starting service there - I believe it is now less than $20. I'll have to dig out a list at the office to illustrate examples of CPEs around the country.

Historically airport costs represent less than 10% of aggregate airlines costs, however, given the dire state most carriers are in they are exerting pressure on airport operators to keep costs down (while, of course, they are also demanding more facility improvements!).