Love your plugin - I'm using it on so many sites now along with Custom Post Type UI and Advanced Custom Fields ... making life so much easier for us here.
Question for you regarding date formats in columns - ACF uses the php and JS formats - today is 19 Nov 2012, so the import format would be
That's working perfectly with all plugins and on the website, but shows as August 21, 1970 as a date-formatted column :-(
Would it be easy for me to amend your plugin to use the date format I've got? Would this make sense to allow flexibility in the Admin Columns interface to define source date format maybe? :-)