Soon: USB 3 will enable the ultimate docking station via 100W power
Quoting USB 3.0 could soon drive monitors, hard drives with 100W of power by Casey Johnston for Ars Technica:
The next USB 3.0 specification will provide up to 100 watts of power to devices, allowing users to power some of the more demanding gadgets on their desks without additional power supplies. The USB 3.0 Promoter Group announced that the standard would allow USB 3.0 ports to power and charge devices like notebook PCs and would remain backwards compatible with USB 2.0 devices.
The most intriguing application of this is a docking station that only needs one cable to connect to a notebook. Thunderbolt  is even better suited for this kind of thing because it supports multiple protocols. But it does not carry enough power: Apple’s Thunderbolt Display
can be considered a docking station, but still needs two cables, power and Thunderbolt.
- Thunderbolt (code-named Light Peak): an overview