I used to play trivia games on Xbox Live. It worked something like this: Answer a series of questions. Every correct answer was worth points. Xbox kept track of my score, and posted it (along with any awards I'd accumulated) in the community space and on my profile card. I had chosen my own username--I could have anonymity if I wanted--and no private information was given aside from what I volunteered about myself.

The leaderboards at Popup Chinese are more similar to this, I suspect, than to a school posting student grades in public. I actually like the community aspect here and hope it gets expanded.

Parenthetically, Popup is a better way to learn Chinese than Xbox Live.