I recently tried to purchase a Google Adword Ad that containted the word "iPod." Upon submitting the ad, I was told that the ad was not approved because I included the trademark term, "iPod."
What idiocy. Does Apple not want us to sell iPods for them? Frustrated, I Googled around and found out that a lot of other Apple resellers have had this problem. Tidbits has a comprehensive list of terms effected, including Apple, iPod, Shuffle, Mac, Mac Mini, iMac, iBook, PowerBook, Power Mac, iTunes, and iTMS.
Tidbits also has a work around, involving restricting your ad geographically and requesting an exception, so if you run into this problem, check it out.