It's not an "open source system", it's more like KDE "Touch"... it may in fact replace hildon-desktop or meego-ui (however it's called), but not the OS... it depends on a linux box with QT and KDE framework...
Maybe it will be possible to test it with Mer+Nemo...
http://community.kde.org/Plasma/Acti...on_ARM_Systems

Greetings!

EDIT: Here you can get it to try on N900... But I am not willing to do this kind of things in my one and only communication device N900... so...
http://bug10738.openaos.org/images/n900/plasma-active/