New SATA-EC300 dual-eSATA ExpressCard

The SATA-EC300 allows you to connect not just one, but two external SATA drives to your laptop computer and supports drive hot swap, 3Gbps transfer speeds, and NCQ for improved SATA performance.

The card will work under OSX (And also under Boot-Camp windows) 

It is supposed to start selling in November 06, in Japan, for about $83. 

Read more here (via Engadget)