Now that the gmail is out, Jason Kottke thinks that they're building GooOS, the Google Operating System: "So. They have this huge map of the Web and are aware of how people move around in the virtual space it represents. They have the perfect place to store this map (one of the world's largest computers that's all but incapable of crashing). And they are clever at reading this map. Google knows what people write about, what they search for, what they shop for, they know who wants to advertise and how effective those advertisements are, and they're about to know how we communicate with friends and loved ones. What can they do with all that? Just about anything that collection of Ph.Ds can dream up."

Well, Jason, let me add that they now know all about our geographical, background and interests information, and that's what exactly an ad company -as you mentioned- wishes for. Just think about combining all that data, and connection gmail accounts with Orkut's and running ads on both. Viola!

Side: Googlemania on Wired has everything and anything about Google. Very interesting stuff.