Very impressive stuff. For what it's worth, I played around with the new audio reCAPTCHA a bit.

    - I heard 50+ distinct words, plus the numbers 1-9
    - Numbers are not written out anymore (e.g. "nine" does not work, it must be "9")
    - You must get 9 out of 10 words correct to complete the CAPTCHA

So they're still working with a very small dictionary of words, and with a little practice it's not hard to nail these consistently (as a human). The extra noise makes it a little more difficult to split the samples, but that's a solvable problem. I bet they can re-break it with their existing program and not too much additional effort to retrain the system.