It's a little on the expensive side, but the hack is vary simple and easy to accomplish. basically you need super glue, this plastic strip from Shapeways, and a set of rare earth magnets from K&J Magnets. You can see the result in the picture above or the video below. The design is quite clean.
Just so you know, this hack won't give you the magic on switch from the iPad 2. It just lets you attach the cover. But it's still a great hack.