I like the standard harmattan squircle... keep things nice and flat and we should be good. Also I don't think that the icons should be the main focus of a new design as there are a lot of other things that need some work (status bar, chat whindow, lock screen,....
I didn't like the message icon from page 4 to be honest. I find it too blunt and plain. I would much prefer if there was some type of outline to it, and a slight gradient