
Find out more about it here.
Very fun looking rig and lots of information about it. Well worth a look.

Squirrely Obstacle Course Part 1 from Josh Burton on Vimeo.
abxPicker provides artists, animators, and character TDs with an intuitive interface for creating and using custom character control interfaces. Using drag and drop, you can create, position, resize, and edit buttons to select character controls.
Features:
* Quickly create layouts using easy drag and drop interface
* Supports background image style, or simplified iconographic layouts
* Auto assign default tools like move and rotate to controls
* Key selection sets with a single button
* Create Toggle buttons for visibility or IK/FK switching or other
* Data is stored in scene nodes for easy portability
* Import/Export to other rigs
* Supports Shift-click to add to selection and ctrl-click to subtract from selection list
* Works with character referencing, rename prefixes and namespacing for pipeline integration
* Only one .mel file (easy to install)
* Includes Test Scene File to try out
Some functions:
- Unlimited characters, sections and poses
- Works with any character, object, node, etc..
- Works with referencing
- Capture thumbnails pose on the fly
- Rename Character, Sections and Poses
- Add / Remove controls poses
- Reorder Sections and Poses
- Mix pose slider!
- You can apply pose and MIX pose in 10%, 25%, 50%, 75%
- Easy to share, just copy and paste /poseman directory or Character directory