"Sibyl" is by the way from greek mythology and referred to a woman who could predict the future, a prophetress. http://en.wikipedia.org/wiki/Sibyl Wikipedia mentions there were as many as 10 Sibyls, although it does not mention that "the" sibyl was also famous for having predicted it's own death... ;-)
Interesting! There is an open source Apache Mahout project for doing machine learning via hadoop. Also have a look at Vowpal wabbit an open source framework for fast SGD for online learning.
Also another interesting point is their use of boosting, since i recently attended a tech talk by facebook engineers where they told us that bagged decision trees while predicting the friends for a user.
