I know what I have to do to game it (reload /newest and look for stuff that is generally interesting and I understand, contribute a neutrally toned slightly technical comment and not follow up or reply to questions), but I will not be doing it (much) because it it goes against two things that I value about comments here:

1) It's a friendly place to converse and ask legitimate questions without getting RTFM or LMGTFY (unless your question is reeeealllly dumb)

2) I value contributions that are presented later, even if they're not as highly scored (this, of course, the reason that comments aren't sorted by raw score), and I don't mind tagging something onto an article, even if I'm joining in late, provided I think it's a net contribution to the site.

I was just going to edit my comment with a link to searchyc.com. It tells me, for example, that my average comment score is ~4, but that my last few comments have been unusually unpopular (or at least unnoticed), which I assume drove me below the threshold. Maybe it would be nice to take the maximum of a user's all time average and average of the last 50 comments - that way users who have historically made positive contributions are given a little leeway to voice unpopular/controversial opinions.

EDIT: Odd, now the edit link is back. Maybe a weird effect of caching or something.