I really like this plugin. My suggestion for future development would be to allow the bulk smush.it feature to target specific directories on your server. This way you could optimize every image in your theme folder, uploads folder, and even plugins folder... Maybe a simple form field that allows you to type in the server path to the folder you want to optimize images in.
Seems like a much needed feature. Especially for users that want to optimize every image reported by Google PageSpeed. So hard to satisfy but so satisfying to see your score go up!
Thanks again for all the hard work. 5 Stars!