Contacts now have access to a bunch of new data field types, FB is included when you'd tap on "Add Field", and navigate to and tap on "Service", and you can see for yourself the new Services available (including LinkedIn). If you've got a relative or other person you want to include, tap on the available person that's tied to you (for me it's "Father") and you'll see more than a dozen of types of linked people, including "Partner", "Child", "Assistant". One of my contact's is the Assistant for one of my attorneys, and I defined her as his Assistant and iOS automatically linked the two contacts.
Tapping on IM type used to get me MobileMe and AIM. Tapping on "Other" yielded 5 Service Labels including "Home", "Work", and "Other", but tapping on "AIM" next to it yielded 10 different IM services including Gtalk, Yahoo Messenger, MSN Messenger, Google Talk - and Jabber! - Skype, FB, and a few others. Cool stuff.