I'm not a Mac user, but came across this and thought you guys would want to know about it.
The Camera Raw team recently provided a release candidate of the Camera Raw 6.4 plug-in and the DNG Converter 6.4 application. For those not familiar with the DNG Converter it’s a free, standalone application that is able to convert over 300 proprietary raw formats to the openly documented DNG file format. When a new proprietary raw file format is released, essentially every new camera model with raw capability, we need to update the DNG Converter so that it’s able to convert that proprietary format to the DNG format.
The PowerPC(PPC) Mac systems, commonly referred to as G4 or G5 systems, represent a significantly different platform than the Intel-based solutions Apple started offering in January of 2006. Due to the differences in software development environments, Photoshop CS5 and Lightroom 3 both dropped support for PowerPC systems in 2010. However, we’ve extended PowerPC support for the DNG Converter into 2011 in order to ensure that customers who are still utilizing PowerPC Macs and are unable to upgrade to the latest version of Photoshop and Lightroom would be able to read raw files from the most recent camera models by converting the proprietary file to DNG and opening the DNG file in a previous version of Photoshop or Lightroom. However, there is increasing overhead required to support the PowerPC code base in the DNG Converter so the final DNG Converter 6.4 update will be the last update to support PowerPC systems.