The PCI-SIG finalized the specifications of PCI-Express 3.0 bus.
Is designed to be backwards-compatible with devices that use older versions of the bus.
The new PCI-Express 3.0 has, resulting in a data-rate of 1 GB/s per lane, per direction.
The first PCI-Express 3.0 compliant devices will come to be in 2011.
You can read the specifications from official source.