According to Notch's tweet (im not sure how to link to the exact tweet but ill quote it)
@MBishop10
@notch Are you planning on implementing the "Skylands" into Minecraft at some point? It was a pretty tight idea. @notch
@MBishop10 Probably, yes. :biggrin.gif: I love the idea. The Ether mod does it great, try it.
Yay!