The Russian student developer, Антонов Николай, is interested in either open-source PRIME multi-GPU support or multi-graphics card hot-switching support to be worked on as this year's Google Summer of Code.
Open-source GPU PRIME support came about a few days over a year ago as an attempt to provide multi-vendor graphics processor offloading / multi-GPU rendering. The PRIME name comes from David Airlie, the author of the original code, dubbing it off NVIDIA's Optimus Technology that was introduced a month prior. Unlike Optimus, PRIME could theoretically work with any open-source graphics driver regardless of hardware vendor. However, the only active work on PRIME lasted for a matter of days and so David looked for someone else to take over this work. Now there may be that chance with the 2011 Google Summer of Code.
The other alternative project that Antonov has expressed interest in is graphics card hot-switching for X.Org. This would be interesting for being able to pop-in a second GPU without blowing out an existing X.Org Server or simply for dual-GPU notebooks to flip from the integrated to discrete graphics seamlessly. It's along the lines of last year's switcheroo work, but more integrated into the X.Org Server for seamless switching.
With these two features, however, there is some display-server-specific work, so any X.Org Server code wouldn't necessarily provide direct benefit to the Wayland Display Server.
There are also other Mesa / X GSoC projects that the open-source developers are hoping student developers will tackle this summer, thanks in large part to Google's sponsorship.