Hi Chris, thanks for your plugin! I've made a tiny tiny contribution to this plugin making it multi-lingual.
I've added a load_plugin_textdomain before your class code, a languages folder, and 3 __('string','mpt') to the 3 sprintf in the code.
You can download this version here.
Bye, Daniele.
http://wordpress.org/extend/plugins/multiple-post-thumbnails/
