Extends ImageField's Image widget (no separate widget!)
Adds a new Focus Scale And Crop ImageCache action.
Adds a new Focus Crop ImageCache action.
Uses a new jQuery plugin that will soon be also available as a separate download.
Integrates with Smart Crop.

The Adaptive image module provides device-appropriate versions of images from your fields.
You can activate adaptive images by adding an adaptive effect to any of your image styles.

The used technique is derived from http://adaptive-images.com/ by Matt Wilcox.
The hard work is done by Drupal core no need for any additional rewrites.
If image styles work on your website, this module will too.