The update looks great, I've re-enabled it on our site.
First thing I noticed is that long usernames will overflow easily, which results in overlapping text.
Also the month/year is displayed, which is superfluous in a chat setting... nobody cares. This also adds to the length problem.
EDIT: I realized that's the same function that provides "1 sec" and "5 min" at closer range. Those are important, but only in the current 24hr window... older than that, there's already a date line.
Fortunately these are CSS tweakable. Anyone who cares, add this to your custom CSS:
EDIT 2: Deleted the scrollbar, for a cleaner look... (Webkit only).