Okay i made it working. I had the Eclipse Java edition installed. I've assumed that Eclipse will download all required dependencies for the plugin and i can use my Eclipse as a mixed Java/C++ development environment. Looks like it's not the case. I've installed the Eclipse C++ edition plus the plugin and it's working now.
I'm wondering why i can't use this plugin with the Java edition. It actually downloaded the CDT components because i can switch to C/C++ view and the Preferences page / project types also expanded with the new options. But the compilation fails.
Anyway, i'm curious if this plugin could be used to program an ATtiny45 this way: http://hlt.media.mit.edu/?p=1229 