It's a bit ironic that after Samsung releases its competitor to the MacBook Air in the form of the Series 9 notebook, the same company is responsible for giving Apple's ultraportable laptop a bit of speed boost. That's because new MacBook Airs are shipping with a new, faster solid state drive apparently from Samsung after initially coming with a Toshiba SSD.
How much faster is the Samsung "blade" SSD (a.k.a. the mSATA form factor that Apple introduced with the Air) than Toshiba's? According to Anandtech, the Samsung SM128C offers 260MB/s read speeds and 210MB/s write speeds, compared to the Toshiba TS128C's 210MB/s read speeds and 185MB/s write speeds.
If you're in the market for the Air, hopefully you'll get a Samsung SSD-equipped version, though you probably have no way of knowing until you bring the notebook home. Such is Apple's way.