Newer announced the availability of a PCI Express 2.0 card bringing 2 eSATA III ports for the Mac Pro (2008 and 2009 models).
When using a PCI Express 2.0 1x line, the card will be "limited" to transfer speed of 500 MB/s for both ports, while SATA III is theoretical able to manage 6000 MB/s for EACH port. So there will be a limitation to 1x 500 MB/s or 2x 250 MB/s, but so far there is no drive able to deliver such peak speed, only some future SSD could start saturating this card. Last but not least, it is unclear in the motherboard will manage deep sleep mode for devices plugged via this card.
