Bobbi Newman has a great blog entry on opting out of Facebook personalization.
The difficulty with opting out is perhaps best expressed where she writes:
Except wait, what’s that bit at the end? What the?
Allowing instant personalization will give you a richer experience as you browse the web. If you opt-out, you will have to manually activate these experiences. Please keep in mind that if you opt out, your friends may still share public Facebook information about you to personalize their experience on these partner sites unless you block the application.
The entire entry — and the comments — are worth reading as the comments reflect a range of reactions.