So I created a derivative of WP Smush.it that runs entirely on your local server using littleutils (which I blogged about previously).
CW Image Optimizer (available from the WordPress plugin site) works just like WP Smush.it except it never uploads your images to a third party. Images are automatically and losslessly optimized using the opt-png, opt-jpg, and opt-gif programs provided by littleutils.
The downside is it requires Linux and littleutils, which most people won’t have unless they put forth the effort to install them. I plan on creating some step-by-step installation instructions for common Linux distributions in the near future, but in the meantime I have a great plugin to use on all my blogs, and because it is in the WordPress repo, I can easily push updates to all my blogs.
Anyways, if you use it, let me know what you think. I’m excited about actively developing this app to make it a great tool for everyone.