Kristian Vättö over at AnandTech is reporting that Apple is no longer using the Toshiba Blade X-Gale Solid State Drive (SSD) for its MacBook Air laptop and has, instead, switched over to using faster drives which are possibly made by Samsung. When iFixit took apart one of the devices, they confirmed that Apple was using Toshiba made TS128C drives, however, SM128C's have been found in a few, more recently built machines. While it has not been possible to confirm if Samsung are behind these, it's pretty safe to assume they are since the 'SM' part almost always represents Samsung on any drive or device.
AnandTech tested the performance of the two drives and found there is a significant speed boost with the SM128C, writing nearly 35MB per second faster. The new SSD has another advantage over the previous one, Native Command Queuing (NCQ), which is a feature added to new devices allowing a hard disk to "internally optimize the order in which received read and write commands are executed" resulting in more efficient speeds.
There is no way to confirm if these are Samsung drives unless Apple makes an announcement, however, all the evidence supports this notion and the SM128C does appear to be noticeably faster in reading and writing data.