Here's what I know about the Surface Docking Station. It will be compatible with Surface Pro and Surface Pro 2, but not Surface RT or Surface 2. The Docking Station is kind of a hulking device where the Surface Pro/2 slides in at an angle and is held in place with by arms on the side that are pulled out to release the tablet. The Surface Docking Station provides a mini Display Port port for video-out. It provides one USB 3.0 port (on the side) and three USB 2.0 ports (on the back). The Docking Station features a 1 Gbps Ethernet port. It also includes dedicated microphone and headphone/speaker ports.
No word on pricing or availability, but I suspect it will ship alongside the Surface Pro 2 later this fall.
As I noted in my article, Surface Pro 3: Desktop PC Replacement?
, this appears to be a serious impressive desktop solution.
Those units will go on sale on September 12, and that is presumably the date that preorders will start shipping.
UK pricing is 165 pounds, or about $281, well over the accessory's $200 price in the US.
--Paul Microsoft curiously claimed yesterday that "the Surface Pro 3 Docking Station is available today for preorder." As it turns out, that accessory has been available for preorder since late June—I ordered mine on June 21, a bit over a month ago.