spoke to soon... found a bug. If stupid users such as myself enter long continuous strings without spaces the comment doesn't wrap. Instead it just keeps on going off screen... exit screen right....
On IE 8 there are quite a few issues. A topic can be created successfully, but you cannot vote (using side buttons) until the page is refreshed. The comments submission box acts slightly differently, changing outline colour instead of background, and the submit button for the comment does not work at all. The error is 'Object doesn't support this property or method' for line 250 in sensibility.js
Also, it mentions on load that IE8 can be run in compatibility mode to support older browsers, however using this mode pretty much screws up the scripts. Buttons do not work, dynamic css doesn't work.
Found 1 problem with Safari 5.0.5 on Win XP. When a new topic is created you can't vote on it until a page refresh has occurred (you can vote on existing topics though) - similar symptom to the IE8 issue?