If you are referencing "Eddie and JoBo" on the Chicago area WBBM-FM (B96), the ownership (CBS Radio) decided to terminate their employment and start a new show in January, 2009.
Ratings are a large part of this type of descision. WBBM ranked 11th and 9th among 18-34 year old males and females, respectively, while competitor WKSC ranked 3rd in both demographics for the same time period (October 2008).
"Eddie and JoBo" will still earn the money due them on the remainder of their contract, which was set to expire in July of 2009. The team will earn nearly 1 million USD for their early termination.