As far as I can tell, the only way to read the Harry Potter ebooks on Windows Phone is via the Kindle application. Has anyone figured out how to read Nook/epub versions purchased from Barnes and Noble on Windows Phone 7 smartphones?
B&N hasn't created a WP7 app yet, and at this point my guess is they never will. There are several ePub readers in the WP7 marketplace, however, and if you get the ePubs directly from Pottermore I believe they are DRM free and should work fine with one of these readers.
