[lmm]

>Passive broadcasting / timeline: Share a status update with your friends, without putting it in an inbox or otherwise forcing them to actively dismiss it. People read your update if they happen to see it, but are not obligated to.

That's what IRC is all about

>Events: Invite people to an event and let everyone see a convenient headcount and list of all the Yes/Maybe RSVPs.

Easy with calendaring

>Friends of friends: Discover new connections among the people you already know—for example, that Bob and Sally are acquainted even though you've never seen them together.

Yes, that's fair. Is that actually useful though?

>Photo tagging: Label each person in a group photo in a listable, searchable way. By viewing photos others have tagged, refresh your memory of who someone is.

Perfectly doable with traditional online photo galleries.

I don't think facebook makes much possible that is impossible without it; the value is all in the integration, as well as the convenient interface you mention.