Looks like nothing is safe from becoming an advertisement these days. A newly surfaced Microsoft patent application proposes to create ads out of human interactive proofs, also known as CAPTCHAs, those lines of fuzzy or distorted text or images used by websites to confirm that submissions are coming from real human beings, not automated online bots.

Microsoft's idea, as depicted in the accompanying diagram, is to present users with a product image, slogan, or some other form of advertisement -- then require them to type in the name of the product or related text to complete the human proof.

But it turns out it's not an original idea. Eagle-eyed tipster "theodp," who alerted us to the filing, also points out this post on the AdLab blog -- from 2005 -- proposing essentially the same thing.

Microsoft says in its patent filing that the approach creates "an effective way for advertisers to deliver their message to a captive audience. Unlike so much web-based advertising that accompanies popular web portals such as search and news sites that users can easily ignore, here the user must actively engage in reading and understanding the content in the advertisement in the HIP (human interactive proof) challenge in order to identify the solution to the challenge."

The Redmond company filed for the patent in February 2008, and the application was made public Aug. 13. We haven't seen any example of Microsoft (or any other company) putting the concept into practice, but if anyone else has, let us know.