>>2I believe the xmonad devs have said that their WM code is too tightly coupled to the X binding to be ported to a different display protocol.
I'm a little concerned about the current lack of diversity in Wayland compositors - it seems like anyone and their dog can write an X window manager but for Wayland the barrier to entry seems to be significantly higher. It'd be nice if the Wayland people could converge on a common interface for implementing higher level WM features instead of just hacking Weston.