One of the GSoC ideas for X.Org this year is to actually focus on Wayland. In particular, the Wayland idea that's been brought up is to work on the remote display capabilities for this promising display server. One of the possibilities for handling remote displays in Wayland is by having a proxy compositor on a remote machine, which would forward the Wayland protocol and buffer updates to the real compositor. Clients running within Wayland would submit where there's damage/changes to the visible surface so that the system is efficient as possible with minimal bandwidth usage. Wayland could be big in 2012.
Ideas for this years summer of code are being collected on the X.Org Wiki but working on this major Wayland feature is the only new idea for 2011 so far this week.
Other ideas proposed in previous years that haven't yet been achieved include an OpenGL 3.2 Gallium3D state tracker, a Cairo state tracker, Gallium3D H.264 video decoding with VDPAU (using shaders, of course), Gallium3D Radeon improvements, automated testing, PRIME multi-GPU support, and even VT switching support for GNU/Hurd and porting DRM to this free software platform.
Let's hope this year's Google Summer of Code for X will be plenty successful (a brief summary of last year's work) with a number of useful projects comign to fruition. Notable X GSoC projects in the past have included Corbin Simpson's work on the Radeon "R300g" Gallium3D driver, Gallium3D XvMC video decoding for Nouveau, R300 GLSL compiler improvements, and kernel mode-setting on vintage hardware.