The PCI Special Interest Group (PCI-SIG) - which manages all of the PCI standards - has just announced the release of PCI Express 3.0 to its members, paving the way for the next generation of motherboards and GPUs.
As with the transition from version 1.0 to version 2.0, PCIe 3.0 doubles the maximum bandwidth and is capable of a hitting eight gigatransfers-per-second. In more relatable numbers, that works out to maximum transfer speeds of almost 1GB/s for a single lane in a single direction. This means that a 16-lane connection has a total aggregate bandwidth of close to 32GB/s.
There's also a new 128b/130b encoding scheme that's about 25 per cent more efficient than the 8b/10b encoding used in the older specifications. The upshot of this is that the bandwidth has been doubled even though the data-rate has only increased from 5GT/s to 8GT/s.
Thankfully, the new spec is completely backward compatible with the older standards, meaning that you'll still be able to use that old GeForce 6800 Ultra in a shiny new motherboard, if you so desire.
Now that the PCIe 3.0 specification is available to the group's members, it's only a matter of time until we start to see products that make use of the interface. However, given the trend to move PCIe controllers out of the chipset and onto the CPU, it could be a while until we see motherboards that can integrate the faster standard. With both Intel and AMD gearing up to launch new processors very soon that won't make use of the spec, it'll probably be a few years before PCIe 3.0 becomes commonplace.