Buyer's Guide: eSATA for MacBook pro
Using eSATA on the MacBook Pro is possible only if it has the ExpressCard/34 slot.
The MacBook Pro has become the MacBook Semi-Pro as of June 2009. Only the 17" model still has the ExpressCard/34 slot as of July 2010.
Future models might benefit from high-speed USB 3.0, but that is likely mid 2010 for Macs.
Be sure to get the 17" model for eSATA support, otherwise there is NO WAY to add fast external storage.
Note that some MacBook Pro models have electrical issues (Apple defect), and do not work reliabily with ExpressCards, see the MacBook Pro compatibility list on the OWC site.
See the review of eSATA cards for the MacBook Pro.