I found an article which details the whole incident from the start:
That turns out to be a pretty good read and therefore I am recommending you go take a look and understand what the big fuss it was all about and why we should not allow companies like Sony install rootkit on our PC.
Most classic quote:
"Most people, I think, don't even know what a rootkit is, so why should they care about it?" Sony BMG's Hesse