While their new Unity desktop will begin shipping in Ubuntu 11.04, their Wayland deployment will not come at this time. It may, however, come with Ubuntu 11.10 if all of the components are in place. Ubuntu 11.04 will continue using the X.Org Server.
Right now Wayland is not really deployed by any Linux distribution (it's not until recently that it became possible to run Wayland with mainline components on Intel hardware and is now supporting Nouveau and Radeon hardware with patches). The first Linux distribution to deploy Wayland will likely be Intel's MeeGo Touch, but that's for more of a niche embedded environment and not a leading Linux desktop distribution where Ubuntu may be the first.
Mark has blogged about the Unity on Wayland on his blog where he talks more at high-level about their decision to eventually ditch the X.Org Server.
While I may be a strong proponent of Wayland, I find it rather optimistic that even with Ubuntu 11.10 they would switch to Wayland by default. I have a lot more to say on the matter, but alas I have a flight to catch now.
Immediately when hearing this news from Mark I asked him what about the proprietary drivers that don't implement KMS (kernel mode-setting), GEM buffers, and other expectations that Wayland has to run... Along with the open-source drivers for old hardware that have user-space mode-setting code-paths and their Mesa support is cruddy, if there's any 3D support at all. There's also the case of brand new hardware, like right now with the Radeon HD 6000 series, where there is no kernel mode-setting support let alone 3D acceleration. Well, here's Mark's quick response to this:
The transition will take time, we will not cut over the whole of Ubuntu by default immediately. We'll work with vendors to support the needed capabilities. This is a strong signal to them to start work on lining up their own efforts to make it a good transition.
While I'd love to see Wayland out there on the desktop ASAP, in reality I would be surprised if it's achieved by Ubuntu 11.10. Unless, of course, there is a very good fall-back system in place for unsupported configurations. It would likely not be done with Ubuntu 12.04 since that will be the next Long-Term Support (LTS) release, which would then make the Wayland release as Ubuntu 12.10, or the release to come in October of 2012.
More information and thoughts on this Ubuntu Wayland adoption soon as I am boarded and have my vodka-coke and Delta GoGo In-Flight Internet.