Doesn't seem to be usable. When I try to import clips, I get this:

Exception raised in /Users/dg/Downloads/hyperengine/Projects/HAVOSX/../../Source/Arme/TArmeQTFileHandler.cpp at line 399 : Unknown exception

The PowerPC prebuilt binary crashes on launch. I suspect this would require a LOT of work to function at all in 10.5.