There are a couple of problems with with non-default date mask.
Administration > Products > Top > Edit Product
--->Click "Calendar" (use following format D MMM YYYY)
date field gets populated with "16 06M 2008"
returns: Product Issue Date didn't match with mask. Use following 'D MMM YYYY'
 
type in the right format and you get a Warning: checkdate() expects parameter 1 to be long, string given in /home/public_html/includes/date_functions.php on line 361
 
 
(is there a better place to post new version bugs?)

Blimey - it is December and they still haven't fixed this bug???!!!
 
How are you supposed to set the date for a product? It does exactly the same when you try to import a date field!