A LOT of readers were kind enough to educate us that GT/s stands for Giga transactions a second. You can see our plea here. That is the time that you need for transfer of a single packet of PCIe bus data from one bus to another. For a fuller definition, go here.
PCIe is defined for 1X, 2X, 4X, 8X, 16X and even 32X lanes. The maximum data transfer for 32 lanes is eight Gigabytes of data per second, per direction. Once the industry moves to PCIe 2.0 the amount of transfer will theoretically double from 2.5 to 5.0GT/s . This will enable 16 GB/s transfer and two times 32X PCIe lanes.