Contextual advertising is the richest kind. If a company can offer advertisers access to people who are likely to want advertised products, it can charge a fortune for those ads. And this is what Google intends to do, and on a massive scale.

I'm going to give it to you straight: I believe Google Voice is free because Google wants to track your phone calls, read your voicemails and text messages and invade your privacy to offer you up on a silver platter to advertisers.

Let's look at the big picture. Google already scans and indexes all your Gmail e-mail messages. It uses Google Maps and its hooks into your phone's GPS to know exactly where you are. With Google Voice, it will know who you call and who calls you and how often. It will know what your voice messages and text messages say. The data extractable from all this is worth a fortune to advertisers -- and to Google.

Think I'm paranoid? Take 20 seconds to prove it to yourself. Go check the advertising that accompanies your Gmail e-mail. Just click through the messages, see what the e-mails are about, then notice how the ads on the right hand side of the page map exactly with the subject of those e-mails. Google computers are serving up ads based on the subject matter of your private conversations.

Gmail's invasion of your personal messages is just the beginning. In the future, I believe the company intends to combine what it knows about you -- friends, family, purchases, location, schedule, blog posts and especially what you talk about in e-mail, text messages, chat and telephone calls -- into knowledge about what you want to buy. It will then show you ads based on that knowledge.