To start off, the Koffice suite and the Amarok media player are already being ported to these platforms, using the newer Qt suite that makes easier portability possible. This is actually a very interesting project. Controversy aside, it would be interesting to see an environment that could be found on Linux, Macs or Windows and remain uniform among them. If you're interested in the project, you can already try it yourself.
While not strictly new, it is actually refreshing to see a project like this being undertaken.