Woah, this is uber slim, but I don't know if how comfortable I feel about that adhesive thing...
http://www.case-mate.com/The-new-iPad-Cases-iPad-3/Case-Mate-The-new-iPad-Textured-Tuxedo-Case.asp
FAQ:
How does my iPad stay attached in the case?
The Tuxedo case uses Magic Tape , an innovative, double-sided adhesive that doesnt leave any residue, to hold the iPad securely in place.
Will Magic Tape lose its adhesive ability?
The Magic Tape can be reactivated with tape or water. Using tape, gently use the adhesive to remove dust and debris from the Magic Tape to refresh stickiness. For water, gently wipe the Magic Tape area with a wet tissue and let the surface air dry to refresh stickiness.
Will Magic Tape leave any residue on my iPad?
Magic Tape is designed to be reusable and removable.
I got my wife a similar case for her Kindle Fire: AYL Frameless Case, and 4 months in, she loves the hell out of it. There isn't the slightest hint that it can be removed short of wedging your fingers between the device and the case. She doesn't even use the elastic closure strap (to hold the cover shut) and it still hasn't moved one iota.
Assuming this Magic Tape is anything like the silicone pad on the AYL, I don't think you'll have any problem. If anything, the smooth aluminum (vs. rubber) back of the iPad, combined with the larger surface area should make for an even firmer hold.