Quote Originally Posted by Phoronix News
The PCI Express 2.0 specification has been ratified by the PCI Express Special Interest Group. The most notable benefit of PCI-E v2.0 is doubling the interconnect bit-rate to 5Gbps. With the PCI Express 2.0 standard, the bandwidth for a PCI Express x16 slot is now at 16Gbps! Other improvements in this latest standard include dynamic link speed management, link bandwidth notification, capability structure expansion, access control services, completion timeout control, function-level reset, and power limit redefinition. More on the PCI-E 2.0 specification can be read at PCI-SIG.
http://www.phoronix.com/?page=news_item&px=NDM4OQ
http://www.pcisig.com/specifications/pciexpress/base2