In looking at that one and reading the description, it's not totally apparent to me that the case allows you to slide out the keyboard. It almost looks like a conventional silicone case, and perhaps you have to remove it to slide open the keyboard (which would stink). Alternatively, maybe there's an opening for the keyboard on the side, but then the back half of the phone would have to be able to slide relatively frictionlessly against the back part of the case.
I wish they had more pictures, or, better yet, that someone would post a hands-on review!
Thanks for the info though - it's good to have someplace to start!