It was connected to a six-bay external hard drive and Apple's Cinema Display monitor at the same time. This is possible because the external hard drive has two Thunderbolt ports. One is connected to the notebook, the other to the external display. Thunderbolt enables the connection up to seven devices this way, without lowering the bandwidth.
The six-bay external hard drive is from Promise. Intel says that there are a wide range of hardware vendors that have adopted Thunderbolt, which means consumers can expect many Thunderbolt-enabled products in the near future.
The demo showcased the unprecedented throughput speeds that Thunderbolt offers--around 700MBps in the photo. Note that existing hard drives offer a maximum speed of just 6Gbps via the third-generation of SATA.
Thunderbolt enables high-speed bidirectional connectivity. It uses both copper and optical cables. The former has a maximum length of 3 meters, and the latter can be many meters long.
The technology can be used with any existing peripheral protocols (USB, FireWire, eSATA) via adapters. It can't be upgraded via add-in adapters, however, and you will need to get a new computer or motherboard.
According to Intel, Thunderbolt is designed to co-exist with USB and will slowly change the way users interact with peripheral devices. In the future, the technology can be scaled to support speeds of up to 100Gbps.