I just stumbled across this review which is something similar to the other half as we discuss it here, only it's designed for use with iphone and not part of the phone.
http://www.youtube.com/watch?v=OMQBhyYGypw

It's called GoStacked, which is a Kickstarter Project, more information on http://gostacked.com/
Turns out, that it didn't receive enough funding by the deadline.