The Clamp-It Corner Clamping Jig is a new product from Rockler Woodworking and Hardware. The jig assembly, along with the Clamp-It Assembly Square, which is sold separately, work together to hold two panels at a 90-degree angle, allowing the builder to use both hands to fasten the joint. The jig includes an extra-wide base, high sidewalls and strong Acme-threaded clamp screws to securely hold panels. Cushioned pads and mounting holes in the body of the Clamp-It Corner Clamping Jig allow it to be anchored in place.
You can find more information on the Rockler website.