Summary: Great plugin that should be a default install on every blog that uses images to optimize them.
Images sometimes have all sorts of meta data attached that aren’t needed, and sometimes they could just be smaller by compressing them in smarter way without loosing any quality. There are several services out there, with Yahoo!’s Smush.it being one of the first and original services. WP Smush.it automatically “smushes” or shrinks the images you upload. The effects can be dramatic. Images that are 5-10% smaller or sometimes even 30% smaller really make for an improved load time.
There are some other services for this.
Installation of this plugin is easy-peasy: upload or install through the backend, activate, you’re done. You can go to your Media screen and smush older images too if you want. The plugin doesn’t have a batch smush function, which would be very cool, if it could just go back and smush your old images one-by-one, though there is a work around for that in this thread on the WP forums.
Alex seems to be responding to queries on the support forum, though he doesn’t reply to them every day or even week.
Well documented and great code, using all of the possible WordPress API’s, including the WordPress HTTP API.