It seems Apple snuck one more “secret” into MacOS X 10.4 (aka Tiger): Apple says that Quartz Composer is a “development tool provided with Mac OS X v10.4 for processing and rendering graphical data”. But that’s a bit of an understatement, as it also happens to be a patching-based tool perfect for creating VJ applications.
It’s not quite Max/MSP or VVVV, but the principles are the same. And since the underlying technology is the full power of the Quartz drawing APIs, OpenGL and Quicktime, it’s a powerful mix. You can find more information at Quartz Compositions wiki, or the ClockSkew and QuartzComps blogs.