Screenshot / Code Snippet
This script converts relative timestamps to absolute timestamps, displayed in your local time zone. For times less than one hour ago, I leave the "x mins ago" relative timestamp, because I think that is more useful in such short timeframes. In all cases, the tooltip is updated to an absolute, local timezone.
Tested on Firefox 5.0 and Chrome 12.0, on Windows 7. Requires Greasemonkey on Firefox.
Do whatever you want, as long as you don't sell it or claim you wrote it. If you make any cool modifications, let me know!