When I switched to iPad from my Kindle, I used Calibre to convert all of my (non-DRMed) mobi/prc files into ePub, which loaded just fine in iBooks.
I agree with JSWolf, I haven't yet found any way to get mobi/prc books into the iPad's Kindle App. It's a real pain. I would go for the Calibre/iBooks approach instead.
|