They have employed a programming technique used by malicious virus programmers: rootkits1. Rootkits have the potential to give someone else remote access and even control of your computer. It is hard to detect and even harder to remove.
Sony claims that consumers are given adequate warning and information in the end user license agreement, and that if consumers *really* don’t like it, they can contact customer services who will instruct you how to uninstall it.
Full story at: PCWorld.com