they released the public beta at NAB which is a re-coded or re-built version
of the windows product that they have had for a few years but now it is cross-platform.
its a really impressive tool that seems to get rid of the bottlenecks and workflow associated with having multiple applications to do compositing and 3D work. imagine maya and shake and the layering of After effects, all in real time. anyway the full release is due at siggraph