SF Elections has Malia Cohen winning over Tony Kelly (although unlike the other supervisor races, they don't seem to be 'calling it' yet, so they're thinking that it could change) after 19 rounds of elimination. If this holds, then it's exactly what I figured - if Kelly couldn't pull it out with four or five left in the race, either Sweet or Cohen would win. I suspect it's actually between Cohen and Sweet at this point, as in Round 18, Cohen's less than 200 votes ahead of Sweet, so in theory, if things break only slightly differently in a recount, then she could conceivably win. Of course, it could conceivably break such that Kelly holds on, too.
http://www.sfelections.org/results/20101102/d10.html
They have it coming down. in order:
1. Cohen
2. Kelly
3. Sweet
4. Tran
5. Moss
These numbers are preliminary, and could change - stay tuned!!