Optane uses the new 3D XPoint memory technology from Intel and Micron, which promises to be a lot faster than NAND flash memory. These new ThinkPad laptops will use Optane as an accelerator, they will feature 16GB Optane SSDs in M.2 2242 form factor, in combination with a regular 2.5" HDD. The main reason for this is because Optane is much more expensive than NAND fash memory, so large-capacity versions for consumer devices aren't affordable for the time being.
Some models of the ThinkPad T470p, L470, L570, T470 and T570 will be equipped with the Optane cache disk. These systems will be launched in January and February 2017, but it's not certain if the versions with the Optane SSD will be available at launch. According to anonymous industry sources, Optane is suffering from more delays.
Support for Intel Optane branded devices based on 3D XPoint memory technology has long been bandied about as a new feature of the Kaby Lake generation of CPUs and chipsets, but Intel has not officially clarified what that means. The plan of record has always been for the first Optane products to be NVMe SSDs, but NVMe is already thoroughly supported by current platforms and software. Because Optane SSDs will have a significantly higher price per GB than NAND flash based SSDs, the natural role for Optane SSDs is to act as a small cache device for larger and slower storage devices. The "Optane support" that Kaby Lake brings is almost certainly just the addition of the ability to use NVMe SSDs (including Optane SSDs) as cache devices.Full details can be read at AnandTech.