Thunderbolt combines DisplayPort and PCIe on a single external connector, and is currently used mainly to connect computers to storage devices and monitors.
For example, the Apple Thunderbolt Display connects to a Mac via a single Thunderbolt cable, yet incorporates audio output, HD webcam, and FireWire 800 and Gigabit Ethernet ports as well as a 2560x1440-pixel display.
As for storage devices, the Promise Technology Pegasus R6 RAID can transfer data at up to 800MBps - significantly faster than the 110MBps achievable by storage connected via USB 3.0. (The USB Promoter Group recently announced plans for a revised USB 3 standard providing raw 10Gbps.)
Current Thunderbolt connectors and cables will work with the new version.