As of Thurs July 3, we have successfully built version 4.9 on all Mac platforms (OS9, PPC, Intel). There have been enough major code changes that it may take a few more days before the Windows version builds properly.
Some technical details: over the past month we have been moving gradually to newer versions of Xcode (the program that converts our C++ code to a working application) and the Mac SDK (base code libraries that make things run on Macs).
Version 4.81 was built with Xcode 2.0 and SDK 10.3, but one part of that code breaks with Mavericks, and probably more things will break with the next Mac OS release this Fall. We’re now up to Xcode 3.2 and SDK 10.6, which probably will be enough to run in the next couple of OS updates. Along the way, we’ve had to remove or rewrite a lot of older code that is no longer supported. Most is in other people’s code, so it can be challenging!