SofProduct's SofShell for iPad 2 ($50) is a bit different from many of the Smart Cover-compatible cases we've seen over the past few months. Instead of a hard plastic shell, it's made of a tacky rubber that's designed to stay put on surfaces even at a deep angle, as shown by the first picture in the set. Protective coverage is good, as there are precisely cut holes for the headphone port, microphone, camera, side switch, and Dock Connector port, a…