1. A method for analyzing one or more policies applicable to a plurality of computing sites that process respective workloads in a distributed computing system, said method comprising: representing said distributed computing system as a state transition model; wherein said representing comprises: constructing said state transition model in accordance with at least one model representing characteristics of said plurality of computing sites, where said at least one model includes at least one of: a site model, a workload model, a workload state model, a site state model, a policy model, an event model or a cost model; wherein said representing further comprises: modeling, at a computing site, an availability of associated resources as a state; modeling, at said computing site, changes to an associated workload and changes to said availability of associated resources as state transitions; and modeling policies that dictate a manner in which said computing site shares resources with a second computing site as constraints on said state and on said state transitions; superimposing a queuing network model on said state transition model, wherein the superimposing said queuing network model on said state transition model comprises: identifying valid states and state transitions for the distributed computing system; and annotating the valid state transitions in said state transition model with probabilities at which the valid state transitions occur and probabilities associated with the policies; and identifying the effects of said one or more policies on said distributed computing system performance in accordance with a solution to said queuing network model.