Canonical is working on the upcoming Ubuntu 14.10 (Utopic Unicorn), but its developers are also trying to improve some technologies that haven't made it just yet to the desktop version, such as Unity 8 and the Mir display server.
Ubuntu users have been waiting for a long time to get a new major overhaul of Unity, the default desktop environment. Unity has been improved over the years, ever since its release back in 2011 for the desktop flavor of the distribution.
Unity received a big update for Ubuntu 14.04 LTS (Trusty Tahr), which was released back in April, but nothing out of the ordinary happened. There were a number of a improvements, but Unity remained largely the same.
A long overdue upgrade is coming for Unity, but it's unclear when it's going to be ready. To make things even more interesting, Unity 8 is already available on Ubuntu for phones, but that's a version slightly altered to work on small screens and within another desktop paradigm.
The version that will eventually make it to the desktop will be a little different. Ubuntu developers are trying to improve Unity 8 and that can be clearly seen from the latest changelog.
According to the developer, the Qt compositor is now going through reviews and approvals, the scope customization ability has been improved, the locking greeter has been improved and it no longer conflicts with Qtcomp, the scope overview integration with backend has been completed, and more bug fixing has been implemented around snap decisions for the shutdown dialog.
Ubuntu developers are also working on a new display server called Mir, which will most likely take the place of the X server in Ubuntu 16.04 LTS, which is scheduled for release in two years’ time. Mir is already in place on Ubuntu for phones, but that is just one platform with a precise set of hardware components.
The desktop is a much bigger problem and it will take some time to make everything work as it should. The leader of the Mir project, Kevin Gunn, explains that a new version, 0.5, has been released, and that's actually a big step forward.
Ubuntu developers are not staying idle and these two major components are improved all the time. We can only hope that users will get a chance to test Mir and Unity 8 together on the desktop, in a more stable fashion than what we had so far.
Until then, you can try to run the Ubuntu 14.10 Daily Image with default Unity 8 (called for now Ubuntu Next), but users have reported problems when trying to test it. It's unlikely that it will work in VirtualBox, but new versions are released all the time.