Hi,
The plugin was perfect but with the upgrade to WP 3.3 start to experience a bug, I set 6 thumbnails for posts.
I can choose an image and set up as a thumbnail but then the 2nd and 3th thumbnail remove after saving and just 1st (default featured), 4th and 5th thumbnail it save.
This doesn´t happend after update.
Hope you can find why? :)
http://wordpress.org/extend/plugins/multiple-post-thumbnails/