Barnes and Noble did not introduce the Pan digital, they are their own separate company who BN has licenesed their ebook store from them to use.
In a sense it's no different than a Nook app on the iPad or Android.
and that is the old model, which they may be phasing out. PanDigital is coming out with a touchscreen eink dispaly
http://news.cnet.com/8301-17938_105-20020061-1.html