Cool idea, but how does it work against spambots? That's the whole point of CAPTCHA. It's not supposed to be a place to add marketing copy. It's supposed to ensure actual humans are using your service. This seems like it's going to be incredibly simple to hack given that the letters are crisp and easily read. I do see that the example CAPTCHA "ads" differ from company to company, but there are still basically 3-4 plain text words in the graphic. If I were making a spambot, I would need to try submitting it 3-4 times until I find the word that works. Too easy...