The announcement was made by Bryce Harrington on the ubuntu-x list. Right now these new packages are to be found in the xorg-edgers repository, but they should be pushed over into the mainline Natty repository in the coming weeks.
X.Org Server 1.10 isn't officially being released until February so right now that is a development snapshot while with Mesa 7.10 they are able to use the released version or a snapshot leading up to the stable Mesa 7.10.1 release.
These versions though for the graphics / X packages shouldn't come as a huge surprise since in early November we talked about the Ubuntu 11.04 X plans. There is no Wayland integration for Ubuntu Natty so those interested in trying out that next-gen tech will be left using one of the PPAs or build scripts for now.