Peter found an Apple Discussion posting which claimed that this cheap SATA Expresscard works on a MacBook Pro. For those who want superfast external hard drive connectivity, you might wish to go from USB 2.0 or Firewire to SATA.
It’s only $50, which is much cheaper than the Firmtek card that sells for $129. You’ll only have to download this driver from Silicon Image, which makes the chipset.
Apparently Addonics also has a pretty nice SATA expresscard which even supports RAID. Called the “2 Port eSATA ExpressCard 34 and RAID5/JBOD eSATA ExpressCard 34“, if someone can try either of these expresscards out, let me know what you think!