Dock

There is no graphics card in this docking stations.

It's all software driven and the USB-Port just tells the monitor what pixels change etc.

We use similiar docks at work to connect our laptops to a full office enviroment ( two monitors, mouse, keyboard, LAN , etc .). It works well for work/text editing etc. But you feel a delay/lag when watching a video in fullscreen for example.

If Dell doesn't offer Software for Mac OS X this dock will definetly not work with OS X.

Edit:
Some people have sucessfully set up two displays on a Macbook Air with an Display-Link Adapter:
http://forums.macrumors.com/showthread.php?t=1597826