Google, the 800-pound gorilla of search engines, has decided to offer a free web-based email service, called GMail. It’s no ordinary email service: they’re offering each user a gigabyte of space for saving messages. That’s 500 times more than Microsoft’s Hotmail.

The catch? Google’s software will place ads alongside your email, based on the content of your messages. If a friend invites you to play tennis, you might see ads for tennis racquets on the same page as the email. This targeting will help Google sell more ads, but it makes some privacy advocates uneasy.

The service isn’t even available to the general public yet, and already a few have raised the alarm. California senator Liz Figueroa threatens to write legislation to stop the service. Consumers have a right to privacy, she says, and Google is trampling on it. Google responds that the ads are chosen by computer programs, not human beings. It’s no different from spam filters, they say, which also look at users’ mail to decide which messages are spam.

Now, GMail itself looks a bit like spam a way to deliver ads you didn’t ask for. But hey, non-Google ads will be treated as spam and filtered out. While Google’s targeted ads are part of the terms of service. Storing thousands of user emails costs money; Google has been honest about where that money will come from. If you don’t like the deal, don’t make the deal. In any case, prohibiting such a voluntary service is out of line. Let consumers decide. Gee, you’ve got freedom!

This is Common Sense. I’m Paul Jacob.