bug -- removeOldAttachments() assumes the upload is attached to a file, so it doesn't remove the original media library entry if it was uploaded straight to the library
	maybe only happens in wpms
copy best practices from BGMP
Once the necessary filter is added to core (http://core.trac.wordpress.org/ticket/16849): Remove custom filter, refactor environment check, and update required version
Look into using http://codex.wordpress.org/Function_Reference/WP_Error instead of your custom one. If that's not appropriate, then maybe write a quick blog post on the method you're using now.
Add internationalization support
remove setting, no need for it. if activated it'll work, if not it wont