mk1004 (2488060) writes "Yahoo news has an article explaining how the text-based CAPTCHA is giving way to ad-based challenge/response. It's claimed that users are faster at responding to familiar logos, shortening the amount of time they spend proving that they are human." Link to Original Source
Quantum Mechanics is a lovely introduction to Hilbert Spaces!
-- Overheard at last year's Archimedeans' Garden Party