CBS, who will televise Superbowl 44, refused to broadcast an ad for ManCrunch.com, a gay dating Web site though it will broadcast an ad that is a Pro-Life ad,features Tim Tebowby, and was created by Focus on The Family.
It appears that at one point CBS rejected issue ads. Now it appears that CBS does not reject issue ads just issue ads from certain ideological dispositions.
CBS and the Superbowl: Trivializing culture for 44 years.
From CNN here and here.