The question about trademarks is often a tough one and one that is revisited time and time again. Barry's first post that I've noticed on this topic about competitors bidding on the RustyBrick name back in 2004. The question seemed to have resurfaced in a HighRankings Forum post, where a user asks how he can protect his website name against trademark violations.
The user is presented with the Google Trademark Policy, which states:
Google takes allegations of trademark infringement very seriously and, as a courtesy, we're happy to investigate matters raised by trademark owners. Also, our Terms and Conditions with advertisers prohibit intellectual property infringement by advertisers and make it clear that advertisers are responsible for the keywords they choose to generate advertisements and the text that they choose to use in those advertisements.
The trademark owner is not required to be a Google AdWords advertiser in order to send a complaint. Please also note that any such investigation will only affect ads served on or by Google. In the case of an AdSense for Domains trademark complaint, an investigation will affect only the domain names of sites in our AdSense for Domains program.
Therefore, Google acknowledges that they will investigate any trademark violations in its AdWords campaign and anyone -- even if they're not AdWords advertisers -- can file reports. This is good news for anyone who is concerned.
A similar thread was discussed last week at Search Engine Watch Forums where members agreed that Google will work to prevent your competitors from using your trademarks.
Google has a number of forms that anyone concerned about trademarks can file for review by the AdWords team. If you are in the US or Canada, you can use the form here. If you are outside the US and Canada, you can use the form here. Basically, Google asks you to fill out a complaint form and then you can either email it to a designated email address, mail it to a physical address, or fax it to one of Google's phone numbers.
Last week, in the same Search Engine Watch Forums thread, a number of users did have concerns about Google enforcing trademarks too strongly. Some more natural search terms were being rejected. Google has responded to these users to let them know that it was a technical glitch that has since been resolved.