VT-d stands for Intel® Virtualization for Directed I/O. "VT-d2" appears to be an informal and internal name for Intel® Core i7 Processor VT-d capabilities. Included in these capabilities are (a) I/O device assignment, (b) DMA remapping, (c) interrupt remapping, and (d) reliability features.
You may get more information about VT-d in detail at: http://www.intel.com/technology/virtualization/technology.htm?iid=tech_v...
Please Click on the link entitled "Intel Virtualization Technology (Intel VT) for Directed I/O (Intel VT-d) Architecture Specification".