So in general the idea "was" to let users build an OS from scratch (well, almost) and light-weight and Unity Linux in fact, has a reputation of being fast as well. But they never had a lot of developers or bug-testers, etc ... so as a result few days ago in their blog, they posted that, they've no choice but to move the Unity-Linux project into Mandriva's repositories from now on.
What does this mean?, is it the end?
Not really actually. To make a long story short, as a Unity-Linux user you'll still receive updates and it'll continue as a separate "Brand" but the developers will be concentrating and operating in a much smaller scale.
In their own words...
The benefits will be that we no longer have to maintain packages as a small team…upstream will do that for us. We’ll be able to focus on meta packages for install, dependency resolution and default desktop environments.So unlike in the past where they'd concentrate on Kernel, desktops and a lot other areas of the distro thus making it a unique, separate OS, but from now on, they'll still be working on and release bug fixes and optimizations, etc for a smaller number of packages in comparison with their older releases.
So in short, no, this is certainly not the end but in a broader way, I think it kinda is :/. But at least on the bright side, hey!, it's GNU/Linux and we can choose the heck out of any distro that we want! :D.