There's a duff query when using lost-password to get back in to the site. It doesn't harm the functionality, but results in an ugly 'not a valid DB handle' message in the page.
"/logout" is not hooked up correctly.
The code for using LaTeX-style line breaks needs more interesting test-cases to really put it through it's paces.
(See Syndication feeds for a current broken case.)
See also, Wiki feature requests