1. A computer program product for virtualizing information technology (IT) appliances comprising a non-transitory computer readable storage medium having computer usable program code embodied therewith, the computer usable program code comprising: IT appliance hosting facilities software implemented at a layer of abstraction above a host for a virtual machine operating system, which is implemented in a layer of abstraction above hardware, where the IT appliance hosting facilities software comprises programmatic code functioning as virtualized hardware upon which a plurality of IT appliance software modules are able to concurrently run, wherein the IT appliance hosting facilities software layer is configured to provide caching, application level security, and a standardized framework for running the plurality of IT appliance software modules configured in conformance with the standardized framework, wherein said IT appliance hosting facilities software comprises: an appliance runtime environment configured to abstract host system details from IT appliance software modules, wherein the appliance runtime environment is completely dependent upon resources of the host; and platform support configured to provide a plurality of services specific to said IT appliance hosting facilities that are able to be invoked by components of the appliance runtime environment, wherein the appliance runtime environment comprises a plurality of discrete components to interact with the IT appliance software modules, said components comprising an administrative interface; a debugging and profiling interface; an appliance interface; an operational interface; system appliance-level macros, user-defined appliance-level macros, a macros appliance instance manager, a security manager, an inter-appliance communication area; a host resources manager, and an operational manager.