Wow, I gotta say Facebook's comment threading is incredibly poorly implemented. It's impossible to see who's said what if you get a notification of a reply to a comment - you have to do a serial search through every nested conversation despite some of one's own comments being preferentially shown (ostensibly to compel one's friends to join the convo).
@lightweight Yes...much like Microsoft. When the end goal is money and power, all other considerations (e.g., usability) are secondary.