I avoid posting 99% of the rumours I read, but this one is from Mark Gurman over at 9to5Mac. His record is almost perfect over the last year and change.
I think this would be a great addition, if they can do it right. I don't think anyone has come up with a good implementation yet on Android or Window's Phone. It didn't make my predictions list, mostly because I didn't think it could happen this year. I'd love to be wrong.