Update 2: TUAW made a mistake in their reporting, there isn’t any reference to iPod4,2 in 4.3 - they had accidentally opened the iOS 5 file twice, instead of the 4.3 file. Please ignore update 1.
Previously, you had to connect up and download the whole OS file -- now it just installs the bits that are new. To sync your photos and music ... to trying it out on the iPad. The iPhone and iPod ...