Awesome man, looks sweet, just a few minor issues:
1. Name/Time header doesn't work when the chat window is at it's minimum width, the time gets bumped down to the next line. I was able to fix it for myself, but I know my fix wouldn't work for everyone (I changed the width of the name from 60% to 180 px, and the width of the Timestamp from 39% to 65px).
2. Status change messages also don't fit the minimum width. Same thing here, last part gets bumped down to the last line. This one I'm not really quite sure how to fix (is there anyway to remove the previous status, as in "Signed off
(was Online)"? It'd fit then.
3. This one isn't really a huge deal, was just wondering why it's not there: the timestamps on grouped messages, as seen here

I'd assume the CSS for it was just too much of a pain, but I'd be curious to see if I could get it to work.
Anyway, overall awesome work, it's the template that finally convinced me to use IEView