Given all this, it seems clear to me that the main purpose for the transcription service is to get your permission for Google to read your voice-mails for contextual advertising.

If all this sounds sinister, it isn't. This is simply where advertising is going. Most people have demonstrated willingness to give up privacy for free stuff. And in fact, contextual advertising itself is desirable. It's better to be pitched products you're likely to want rather than products you don't want.

So if and when you get your Google Voice invitation, enjoy its powerful features. But have no illusions about what's the service is all about. Google is paying you in the form of great new service for the opportunity to tell advertisers exactly who you are and what you want.

In other words: You're paying for Google Voice -- not with money, but with your privacy.

Mike Elgan writes about technology and global tech culture. He blogs about the technology needs, desires and successes of mobile warriors in his Computerworld blog, The World Is My Office. Contact Mike at mike.elgan@elgan.com, follow him on Twitter or his blog, The Raw Feed.