Compiz 0.9 was supposed to be released by the end of 2009, but that didn't happen and now seven months later it's actually available. Compiz 0.9 merges Nomad and Compiz++ into Compiz (and also drops Compiz Fusion) so Compiz is now effectively rewritten in C++. Beyond moving from C to C++, Compiz 0.9 brings a brand new development API, moves the rendering off into the land of Compiz plug-ins, uses a different build system (cmake rather than automake), and there are tons of other internal and external changes.
With the Compiz rendering now being split-up, there is the capability to have rendering back-ends such as those that leverage the X Render extension or Clutter. With these changes, Compiz could also run as a non-compositing window manager.
Compiz 0.9 is considered an unstable release while once stabilized it will be released as Compiz 0.10. The release announcement for Compiz 0.9.0 can be found on the Compiz mailing list.