Let’s get clear on the distinctions between these two forms of intellectual property law:
Copyright is “a form of protection provided by the laws of the United States (title 17, U.S. Code) to the authors of ‘original works of authorship,’ including literary, dramatic, musical, artistic, and certain other intellectual works.”
Trademark (same link as above) is “a word, name, symbol or device which is used in trade with goods to indicate the source of the goods and to distinguish them from the goods of others.”
You can’t copyright a title or a short common phrase. But you can trademark a word or phrase to identify your products. So the Chicago Reader cannot take action against Playboy or anyone else who uses the phrase “the straight dope” in an article, even in the title. But ** Anamorphic ** is right that Mr. Hefner would probably get a letter from Unca Cec’s lawyers if Playboy started running a column called “The Straight Dope.”
Recognizing that it would be unfair to allow anyone to have exclusive trademark rights to a word or phrase, the law allows for the same mark to be issued to more than one person or company if there is little chance that consumers would be likely to confuse them. So a trademark on “The Straight Dope” might also be issued to, say, a head shop.
Ringo is half right: you can trademark the specific graphic form of the mark or the word/phrase or both. You can also trademark a logo or other graphic image (e.g. the Nike “swoosh”).