I spoke to a lexicomp rep today and was told a little more about pricing and release date. He told me that the pricing will be the same as all their packages they currently offer for mobile devices EXCEPT as of right now no student or group discounts because the software is being offered through the iTunes store. The release date will be in the next couple weeks as they have already submitted it to Apple for approval. You can see some screenshots of the software here
http://www.lexi.com/individuals/iphone/
http://www.lexi.com/individuals/iphone/