An interesting article here. It's from Daily Finance, so its focus is on investing in the publishing industry. Thus the focus is on how shifts in publishing affect companies, not individual authors.
"...the battles are not really between Amazon's Kindle, Apple's iPad, Barnes & Noble's Nook, and Sony's Digital Reader -- as most of the press will lead us to believe -- but between traditional publishers weighted down by 19th century printing, warehousing and distribution assets and an emerging generation of nimble e-publishers who will supply content to the reading tablets that will be ubiquitous within ten years." The article also says that "Apple and Amazon are frenemies."