I've just downloaded the new PB 3D preview but it shuts down immediately. The console is logging an "Unknown kernel type" error. I'm on a Mac Book Pro with OSX 10.6.6
Same here, it's not a crash due to a pixelbender kernel. It's the macintosh console stating the application crashed due to unknown kernel. So the PixelBender3D app does not even boot up and that's the problem.
Can you post the details of your system (OS version etc.) the exact command line that you're using and make sure that you have the latest release of the PB3D tools from here: