With ultrabooks becoming increasingly popular, hard drive maanufacturers have started to focus more on thinner form factor drives, as well as hybrid.  Seagate have the Momentus XT which pairs a spinning hard drive with a few 8GB of NAND flash, but we widespread OEM use has yet to come.

Western Digital have lagged behind in this respect, but have now announced a 5mm thin hybrid hard drive which has between 8GB and 32GB of  NAND on-board. These 5mm drives will have an innovative SATA and power adapter, required due to the smaller size of the drive. 500GB will be available in 5mm and a 1TB version will come in at 7mm thick. There is no word yet on the architecture of the caching process.

When it comes to data recovery and hybrid drives, all of the data is stored primarily on the disc itself. Only a cached portion of the data is stored on the NAND, so this will not have any major negative impacts on the data recovery process.