Well what do you know! It seems Apple filed a patent back in Q4/2009 where they show off their ideas on how to bring a Hybrid E Ink-LCD display to an iPhone in the near future. Not really sure why has Patently Apple chosen to dig up more information about this patent until now, but it could mean that Apple has finally figured it out for the next generation iPhone.
An E Ink only phone would surely die on arrival because it’s only good for displaying text, but if Apple does figure out a way to bring you the best of both worlds, I’d say they have a winner product. Amazon’s Kindle is built around this E Ink technology and has found great acceptance from the market so far, so it makes all the sense in the world for Apple to learn from that.
Aside from that, the patent also mentions that you’ll be able to split your screen in four separate working areas and have only part of your screen working in E Ink format. In the end, time will tell.