The virtualization vendors such as XenSource, VMWare, VirtualIron and Microsoft have touted some very high consolidation numbers. Intel has devoted a signifcant amount of time and effort to outline the new technology from a processor workload perspective, regardless of vendor virtualization platform, to outline how quad-core technology works to achieve the 8:1 ratios. Enclosed are some helpful links to explain the differences and benefits of the quad-core platform.
Intel: "Increase performance without increasing cost"
Intel: "Cost savings calculator"
Intel: "Expanding Value through Accelerated IT Refresh" - pdf
Sun: "Server Consolidation Using Quad-Core Processors" - pdf
: