Going back to February were public patches for implementing a RandR protocol for Wayland's Weston. That work was revised in late March and is now up to a third revision for a protocol specific to Weston at this time for allowing various display adjustments.
The RandR extension is obviously tied to X.Org, but similar functionality now exists via a "wlrandr" protocol extension. The "wlrandr" extension allows for switching modes and also ships a weston-switch-mode utility for changing modes just like xrandr.
Version 3 of the new Weston RandR patches provide support for handling multiple output operations in one commit, new timing flags support, a new RandR data type interface, above/below move actions of a output, and various other new code that's now ready for review by Wayland developers.
More details on this Weston RandR work can be found via the announcement that was sent to the Wayland development list.