It's "just a feature" (I don't agree with this, btw - it's a service) with about a billion separate implementations (brightkite, facebook status, jaiku, friendfeed, tumblr, etc, etc), and yet it still exists as the market leader in the space even though pretty much all of these sites do it "better" in some way.

Did you write this article simply as linkbait, or do you really believe it?