Apple's MacBook Air and PC ultrabooks use new solid state drive (SSD) modules. But don't count on any cross-platform or cross-manufacturer compatibility.
While working on a recent AnandTech review, editor Anand Lal Shimpi wondered whether he could swap a SSD from a ASUS Zenbook and a MacBook Air. Great idea, but no.
The standard SATA spec calls for a 7-pin data interface and a 15-pin power interface for a total of 22 pins. The ASUS Zenbook/Zenbook Prime SSD features a split connector with 12 pins on the larger portion and 6 on the remaining - I assume for power and data, respectively. The MacBook Air SSD on the other hand has a 12 + 2 pin configuration, with a large power, ground or non-connected pin occupying the remainder of the smaller part of the connector. It's always possible, albeit unlikely, that both ASUS and Apple settled on the exact same pinout for their interfaces, thus making these two form factors electrically compatible but with slightly different configurations. However if you line up the two connectors you'll see that there are physical differences that preclude using one in lieu of the other:
Of course, this also means that the PC drives aren't compatible with Other World Computing's various enclosure kits such as the Mercury Elite Pro mini and the Mercury On-The-Go enclosures. In a quick search, I didn't see a PC enclosure kit for the ultrabook-style drives, but I'm sure one must be on the market.