[Max Taxable]

Hmm... Seems my answer does lie here: http://en.wikipedia.org/wiki/XRumer#...count_creation

As per the latest update to XRumer 7 the software is able to automatically register e-mail accounts on mail.ru (Russian IP addresses only) and Gmail. Support for creating e-mail accounts in an automated fashion on Hotmail and AOL have been completely removed. The technique employed by XRumer to bypass the CAPTCHA protection in Gmail and mail.ru is Averaging. A captcha is a challenge-response test frequently used by internet services in order to verify that the user is actually a human rather than a computer program. Commonly, captchas are dynamically created images of random numbers and/or letters. These images are distorted in some way so that the human eye can still recognize them but with the goal to make automatic recognition impossible. Captchas are used by freemail services to prevent automatic creation of a huge number of email accounts and to protect automatic form submissions on blogs, forums and article directories. [3] As of November 2012, Xrumer has once again cracked Recaptcha, and is able to successfully post to Forums/Blogs that use it.

Averaging is a common method in physics to reduce noise in input data. The averaging attack can be used on image-based captchas if the following conditions are met:

The predominant distortion in the captcha is of noise-like nature. It is possible to extract a series of different images with the same information encoded in them. Averaging of a series of images can be used to improve image quality (reduce distortion, or improve signal-to-noise ratio, so to say) of captchas and hence to make them more easily recognizable by OCR (optical character recognition) systems.

The fact that noise and payload behave differently on "reload" is exploited. This allows the program to separate them and hence defeat the captcha without the need for a sophisticated algorithm.