A bit late on seeing Curts post, but it strikes me as being designed by someone who has forgotten why captchas were developed in the first place, to stop spammers. By scr.im offering a selection of possible answers, all a bot need do is guess. It'll be right 1 in 9 times, so all scr.im have done is asked spammers to try a bit more often, hardly much of an inconvenience.
timns- Those Recaptcha and Google captchas work on the pronciple that they are using you to translate OCR'd text for them. They present two words but only know one of the words themselves. So if one word is seriously scrambled, or contains number, symbols, foreign punctuation, etc then you can be pretty sure that's the one they don't know. You can actually just enter a space for it, or you could purposely enter an incorrect word to mess with them
Either way, once you get the other word right you're accepted.