For years Yahoo has tried to push their motto, 'Do you Yahoo?', trying to make their brand name into a verb. Google has been trying, in vain, the opposite, to extend that they started sending trademark letters to websites using Google as a verb. But the fact that Google is a verb and Yahoo isn't goes a long way in explaining the differences between the two Internet powers.
The search engine wars are starting up. Yahoo dumped Google and we're all waiting for Microsoft to get their secret weapon out and kick Google. Well, maybe not in this version, or the next, but how does 3.1 sound. But let's concentrate on Google and Yahoo for a bit and especially the verbness of both names.
Yahoo has always tried to be a complete internet solution, from discussion groups, to mail, to homepage building and commerce. Yahoo doesn't want to be a portal, a place where you start your Internet adventures, but wants to be the Internet or at least a lifestyle on Internet. That's why they would like to be a verb. Do you Yahoo implies that Yahooing is a better way of internetting.
Google is the opposite. Google doesn't try to be everything for the Internetter, Google does only one thing: search. Whether in newsgroups, shops, images or the plain old web, searching is what Google does best. It makes to google as a verb much more attractive than to yahoo, which is why Google doesn't want the verb to become popular; before you know it, people are googling at the new search engine of Yahoo.
Yahoo wants to be everything, wants to be a lifestyle and thus to be a verb. Google wants to be one thing and wants to be unique and therefore doesn't want to be a general term like a verb.