Pekka Paalanen published a patch-set that's ready for pulling to do surface transformations. Display surfaces within Wayland can now have any number of arbitrary projective-linear transformations. Input coordinate transformations are also handled as part of the patch-set, which in the process of implementing the coordinate system was cleaned-up. Right now this is only 2D-to-2D transformations being handled.
As far as why Pekka's working on surface transformation support within Wayland itself, his use-cases in mind are in order to have a zoom effect / full-screen scaling so that they work in a uniform manner within the land of Wayland and "it's bling, like wscreensaver ;-)"
Find his patch-set on the mailing list.
If you're itching to try out Wayland right now with the Qt5 tool-kit, Tiago Vignatti has written a detailed guide covering the build/setup process. This guide covers building Qt 5 from Git and how the Qt back-end can be dynamically changed to handle Wayland. Qt5 window abstraction allows applications to run nicely whether it be X.Org or Wayland (or the various other display back-ends), though applications can optionally interact directly with the Wayland surface and display. The Wayland Qt5 guide covers all these details.
Wayland will be a big topic next weekend at FOSDEM 2012 in Brussels, Belgium.