This was a blog on Mark Shuttleworths announcement

ORLANDO, FLA. -- Mark Shuttleworth, founder of Ubuntu
http://www.ubuntu.com/> and the company behind it, Canonical, surprised
the hundreds of Ubuntu programmers at the Ubuntu Developers Summit
http://summit.ubuntu.com/uds-n/> when he announced that the next
release of the popular Linux operating system, Ubuntu 11.04, would use
Unity http://unity.ubuntu.com/> as the default desktop interface
because "users want Unity as their primary desktop."

Unity is Ubuntu's new netbook interface that, while based on GNOME
http://www.gnome.org/>, is its own take on what an interface should
look and act like. To make it work on the desktop instead of on the
netbook, where one foreground activity at a time is the rule,
Shuttleworth admitted that Ubuntu had "A lot of work to do around
windows management." That said, "We are committing to the biggest change
on the desktop. Unity will become the default, when we're sure that it
will work."

Shuttleworth hopes -- expects, really -- that this switchover will be
completed by the next release. "Lots of people are already committed to
Unity -- the community, desktop users, developers, and platform and
hardware vendors." In particular, he noted, original equipment
manufacturers (OEMs) favor Unity. They're happy to ship it.

In an interview after the presentation, Shuttleworth added that Dell
www.dell.com/.../linux_3x?c=us&l=en&cs=19>,
which he said had sold several million Ubuntu desktops, laptops, and
netbooks, supports the project. In addition, Canonical has overarching
deals in place with Lenovo http://www.lenovo.com/us/en/#ss> and Acer
http://www.acer-group.com/public/>. These arrangements may lead to
these major PC OEMs releasing Ubuntu desktops as well.

One reason Shuttleworth cited for this switch is that that using one
interface for both netbooks and desktops will improve quality assurance
and make it easier for OEMs to integrate and support Ubuntu across their
PC platforms. In short, "There will be no fault-line for OEMs between
desktops."

For users, the new Ubuntu Unity will default to either a single window
for a single foreground application on netbooks, or to multiple windows
for a multi-foreground interface on a desktop or laptop. Of course,
users can choose whichever of these environments they wish, or use the
GNOME desktop or the closest thing GNOME has to Unity, the GNOME Shell
http://live.gnome.org/GnomeShell>.