There's a
thread for plugin ideas over at the plugins forum. Maybe someone is interested in this too or just plain helpful.
Edited to add: There are tweaks available to control how Calibre displays and interprets the dates. The tweaks are gui_pubdate_display_format and gui_timestamp_display_format. To change the setting, go to preferences->advanced->tweaks, select the tweak you want to change in the upper text field, paste it down to the lower and change to your liking. Documentation is prepended to each tweak. Remember to restart for the settings to take effect.