Matt Zimmerman has announced the Ubuntu Mobile and Embeddded Edition on the ubuntu-devel-announce mailing list:

Three years on, it is clear that new types of device - small, handheld, graphical tablets which are Internet-enabled are going to change the way we communicate and collaborate. These devices place new demands on open source software and require innovative graphical interfaces, improved power
management and better responsiveness.

Intel, specifically, have announced a new low-power processor and chipset architecture which will be designed to allow full internet use on these mobile Internet devices.

To fulfil the aims of our mission and in response to the technical challenges that these devices pose, we are announcing the Ubuntu Mobile and Embedded project.

We will start more detailed planning at the Ubuntu Developer Summit next week in Seville and the first release of this edition will be in October with Ubuntu 7.10. If you are interested in the project, please get involved. We will be working through our normal development processes on Launchpad, the developer mailing lists and IRC.

Finally, we are delighted to be working with Intel on this version of Ubuntu. Intel are making significant contributions of technology, people and expertise to the project.