Fusion Drive combines 128GB of super fast flash storage with a traditional hard drive. It automatically and dynamically moves frequently used files to flash for quicker access. With Fusion Drive in your iMac, booting is up to 1.7 times faster, and copying files and importing photos are up to 3.5 times faster. Over time, as the system learns how you work, Fusion Drive makes your Mac experience even better. All while letting you store your digital life on a traditional, roomy hard drive.
The new upgrade option is an additional $250 on top of the $1299 base price.
Read More [via MacRumors]