From the horse’s mouth
DisplayLink have updated their class driver for their USB-based “plug and display” infrastructure in order to satisfy Windows 8’s needs. Primarily this is to benefit tablet computers, convertibles, Ultrabooks and other similar portable Windows 8 computers to allow them to work with larger screens or display-adaptor modules and expose the displays to what Windows 8 can offer.
For example, there is the ability to use both the Start user interface and the regular desktop user interface across the different displays that are linked using this system. Similarly, a manufacturer could offer a touch-enabled monitor-dock that uses this connection interface as a point of innovation and Windows 8 users can still use this touch-enabled screen as a control surface for their portable Windows 8 computer.
It still can work across all USB connection types through the use of data-compression techniques for the common USB 2.0 setup. As well, the adaptors will support a resolution 2560×1152 per screen depending on the bandwidth, which can allow for the new high-pixel-density displays.
What I see of this is that the USB-based expansion modules (docking stations) will still be relevant to the Windows 8 touch-focused computing era as they are with Windows 7 and before.