It's be nice if we could customize the formatting of the date header in the mail list view. For example, to me it doesn't make sense to display
Thu, November 29, 2012
for today's header. If the header said "Today" it would be more intuitive. Same for the day before today - "Yesterday".
As for the days before that, I am not sure why the weekday name is abbreviated, but the calendar name isn't. Perhaps the farer I go back in time, the more important is the month name, but at least for the more recent days, it would make more sense to use the full weekday name and to abbreviate the month name instead. Or, if you would like to be consistent, abbreviate them both. Or even better, allow us to customize it.
Cheers