Kai Mast, a student developer, has thought about implementing a hot-replace server for Wayland. It could be used in cases where Wayland crashes or the user wishes to change the window manager / compositor. Though in doing this hot-replacement it would need to support proper disconnecting of Wayland clients, client discovery of new servers, and improvements to resource handling, among other work. It's an interesting concept, but may be a bit much to implement in the course of the summer with Wayland still being a work-in-progress and moving target in terms of support.
The proposal can be read on the Wayland mailing list.
Other X.Org / Mesa proposals this year include Gallium3D OpenCL, VP8 VDPAU state tracker, and various other work.
There was also KDE talk of KWin support for Wayland or at least re-factoring the core to make the support easier in the future. On the Low-Level Virtual Machine front there's even talk of an LLVM-based Direct3D HLSL compiler.