Yahoo recently filed with the US Patent and Trademark Office for two new trademark or to be more precise, service marks.
First, Search Engine Roundtable points to the Yahoo Moves To Trademark Y.com discussion in our Search Engine Watch Forums about Yahoo applying to trademark the term "Y.com." This filing was made on August 22, 2005.
Next, three days later on August 25th, Yahoo filed to trademark/service mark an oval and exclamation point logo. You'll see an example at the top of the application.