Business Insider says a source has told them that Apple is working on integrating Facebook directly into the next iPhone OS. This would mean the use of Facebook Connect to bring contacts directly into the phone (which we've heard as a rumor before, and which would make sense, considering that the Android OS already does that). BI also suggests that Apple might be working on features like showing Facebook pictures of your contacts when they call or building the Facebook API into the official iPhone SDK. This would allow app creators to use Facebook information in their apps directly through the iPhone's code interface.
It's all rumor and speculation at this point, so don't get (too) freaked out about Facebook's privacy problems spreading off to the iPhone just yet. However, it's true that Facebook is quickly becoming one of the Web's biggest sources of personal information, and qualms about privacy aside, Apple would do well to at least catch up to Android and start getting the hooks into the main OS.