The new firmware adds several new capabilities to the wireless system. Two of the big ones are Rear Curtain Sync and Pre-Flash Boost:
“PocketWizard’s rear curtain sync allows the photographer to set the shutter speed at which rear curtain sync automatically engages while optimizing the timing of rear curtain sync to fire at the absolute end of the shutter opening. Pre-Flash Boost provides enhanced E-TTL performance when using flash diffusers, doing bounce flash, or at ranges just beyond the normal E-TTL capabilities. By increasing the pre-flash power, PocketWizard has offset the loss of light in these challenging E-TTL situations.” -PocketWizard
The new firmware also adds automatic camera detection, which allows the system to determine appropriate sync speed for High Speed Sync mode. Compatibility for the Canon 7D has been added, along with compatibility for the Metz 58 AF-1.
Additional details about the updated firmware are available in a PDF file from PocketWizard, which can be viewed here.
Download info for the firmware can be found here.