While many people still don't use PCI Express and AGP is still selling well, Intel is already preparing PCI Express 2. The company announced at the IDF the first PCIe II products are expected in 2007 or 2008.
PCI Express 2 will feature higher performance at 5GHz PHY, device virtualization, trusted platform and different form factors.
However, PCI Express will stay compatible with PCI Express 1.x so will still be able to use 'old' hardware as it has the same power requirements and clock architecture. But it should be cheaper.
Intel claims voltage margins aren't the problem with the current generation but jitter is. So they plan to make the jitter budget a fundamental requirement for this second version.
PCIe II will have five GHz devices to run at 2.5GT/s or 5.0GT/s and the transmitter, receiver, reference clock and channel must all be 5GHz capable to get that kind of performance.
There's also support for virtualization which will enable multiple operating systems to simultaneously use and share the PCI Express devices.
OS improvements can lead to increased IO attacks on systems, so PCIe II will try and include better trusted computing. There will be a trusted configuration space, and a trusted configuration access mechanism will be included with modifications to the trusted platform module (TPM) to enable that.