"MySQL retrieves and displays DATETIME values in 'YYYY-MM-DD HH:MM:SS' format." This is from mysql site. You can store only this type, but you can use one of the many time format functions to change it, when you need to display it.
For example, one of those functions is the DATE_FORMAT, which can be used like so:
SELECT DATE_FORMAT(column_name, '%m/%d/%Y %H:%i') FROM tablename
~ Answered on 2011-12-01 08:01:05