This is a really cool project. I could see it being very useful for bitcoin sites, as long as it confirms quickly. Sux for people who don't have a smart phone though.
If you click the QR code on
https://bitcoincaptcha.com or any other place where it has been implemented and have a Bitcoin Wallet installed, it will automatically open up with the predefined amount to complete the challenge. No need for a smart phone. Try it out and see if it works for you.