When I saw Suw's announcement that she and Chris had met and were in love I was happy for them, but not surprised. Sure, I had seen them talk in chatrooms, but the real clue was some information leakage from iChat AV.
It's presence information shows you when people are online, and when they are available for audio and video chat. So for a couple of weeks beforehand, I would glance at my buddy list and whenever Suw & Chris were online, they'd both have their A/V icons dimmed, as they were together, video-chatting. Congratulations.