My students noticed the following font bug. Most of them are using "native unicode fonts", rather than downloading the jsMath fonts. One student noticed that "floors and ceilings are reversed". In other words, using unicode fonts, $\lfloor$ gets displayed as $\lceil$ should, and $\rfloor$ gets displayed as $\rceil$ should, and vice versa.
An example can be found at http://slugmath.ucsc.edu/mediawiki/index.php/User:Marty/Sandbox
The problem seems to only occur with native unicode fonts.
Thank you for your assistance!
- Marty Weissman