The storage technology, which was launched this past Tuesday, combines flash and traditional hard drive technology to create a hybrid system that "combines the performance of Flash storage with the capacity of a hard drive."
According to the FAQ, Fusion Drive requires a special version of Disk Utility. This release is "unique," and Apple mentions that you cannot use older Disk Utility releases with the new setup.
Fusion Drive will allow users to add at most one extra partition. Boot Camp will not be supported on the 3TB configuration.
The write-up surveys a few other points like restoring Startup Disk preferences after resetting PRAM, how to use Fusion Drive with Target Disk Mode, and offers warnings regarding the sustained capture rate of Fusion Drive for video editing applications
It's well worth a read if you've just ordered a Mac equipped with the new tech. For more Fusion Drive news and notes, check out Dave Hamilton's post at Mac Observer.