I'm not sure there's any reason for lawyers and money to be involved. A trademark in the U.S. protect marks used in commerce, so I would think that the authors

I'm not sure there's any reason for lawyers and money to be involved. A trademark in the U.S. protect marks used in commerce, so I would think that the authors of Go! would have to have used the name in a commercial venture prior to Google's announcement. It appears that Google is not asserting trademark protection on the name, either, so there really doesn't seem to be any legal case at all - it looks like both parties can use it. From uspto.gov: A trademark includes any word, name, symbol, or device, or any combination, used, or intended to be used, in commerce to identify and distinguish the goods of one manufacturer or seller from goods manufactured or sold by others, and to indicate the source of the goods.