From the nytimes.com
The researchers examined public databases of 7.1 million public keys that are used to secure e-mail messages, online banking transactions and other secure data exchanges. The researchers employed the Euclidean algorithm, an efficient way to find the greatest common divisor of two integers, to examine those public key numbers. They were able to produce evidence that a small percentage of those numbers were not truly random, making it possible to determine the underlying numbers, or secret keys, used to generate the public key.
Maybe this is why they are called pseudo-random number generators?!