http://www.dc949.org/projects/stiltwalker/
https://gist.github.com/2932918
These are the examples of how technology is catching up with captcha. What are the alternatives? We've been trying to think of the way how to make captcha obsolete, and basically this is the story behind it. While doing some testing of the APIs for my company (we made REST APIs for any developer to access with ease the telecom blackbox goodies such as SMS, USSD, etc.)
I came to the conclusion that it would be a whole lot better to implement a SMS or a USSD verification of the user using their mobile phone.
Then it came to me to leave a possibility for the user to access our website (www.parseco.com) and register using only his mobile phone (no emails!).
What do you think about the idea?