Yell-o-pages might confuse some people to thinking that they are the real thing, and not some generic knock off. People may associate Yell-o-Pages with the real Yellow Pages. If I went into a store and asked for "coke" and they only had pepsi in house and told me this in response to my question, this is not pepsi using coke symbols to pretend to be the authentic supplier of "coke." I think a google search ads is similar to putting your brand on the same shelf as competitor brands, but because the source is not confused, its not infringement. If the sign on an aisle read "transformers" and there were go-bots on the shelf next to the real transformers, go-bots do not need to be removed from the aisle. The go-bots are using the recognized name of transformers for better product placement, but they are not saying "we are transformers" which may be the integral difference.

Decius wrote:

Shannon wrote:
But isn't the purpose of a Trademark to keep someone from stealing a source identifier? Finding a competitors advertisement in a search for a trademarked company does not confuse who the source of the trademark is.

The reason that you want to keep someone from stealing a source identifier is so that person cannot fraudulently profit from the name recognition, branding, and advertising done by the real source. For example, you've heard of the "yellow pages" and you go looking for the "yellow pages" and you pick up the "yell-o pages" instead. The proprieter of the "yell-o pages" is profiting from the advertising that the "yellow pages" is doing. Purchasing advertisements on someone else's name does precisely the same thing. The first person spends money building their brand, and you get to reap some of the benefit from piggybacking on their name recognition.

RE: Google's broken Trademark precident