mk1004 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.
"Conversion, fastidious Goddess, loves blood better than brick, and feasts
most subtly on the human will."
-- Virginia Woolf, "Mrs. Dalloway"