The plans back in November of 2010 were for Ubuntu's Unity desktop to eventually run on Wayland rather than the long-standing X.Org/X11 Server. Mark acknowledged back then that it would likely be a gradual transition and it still will be the case. Wayland 1.0 was recently released, but it's still not ready to take on the world with missing features, not all drivers/hardware being Wayland-compatible, and other shortcomings.
Mark's announcement did spark some new Wayland activity amongst other individuals, but to this day Canonical isn't a significant contributor to Wayland or the Weston compositor -- their patch contributions are rare. Other companies and individuals are doing much more to advance Wayland than Canonical.
Originally Canonical set out for some ambitious Wayland plans whereby Wayland/Weston would serve as a system compositor for Ubuntu 12.10 but ultimately those plans were scrapped since both ends of the stack weren't ready. The Ubuntu Developer Summit was last week in Copenhagen and no big Wayland plans were drawn.
Wayland/Weston will continue to be packaged in Ubuntu 13.04, but it's unlikely the system compositor will be ready in the next six months nor the other requirements to begin transitioning the Ubuntu desktop from X11/X.Org to Wayland. At least now the Wayland protocol and API are stable and future releases will be backwards compatible so tool-kits and Linux desktop applications can begin the process of creating stable Wayland ports. With X.Org Server 1.14 in March is where XWayland should be merged for nicely allowing legacy X11 applications to run smoothly atop Wayland with a dynamic root-less xorg-server.
If the stars align we might see some of Ubuntu's Wayland vision become a reality for Ubuntu 13.10, but that still might be a tough bet. Ubuntu 14.04 is Canonical's next Long-Term Support release so they will be more cautious around that time-frame and not introduce any big X.Org/Wayland breaks, which may lead to Unity on Wayland not becoming fully realized until Ubuntu 14.10 -- four years after Mark shared his vision for this major Linux desktop transition.