1. A method of mediating in a virtual resource provider, comprising: provisioning virtual resources associated with hardware resources for use by customers of the virtual resource provider, wherein the virtual resources include virtual machines; managing the provisioned virtual resources using a plurality of control plane modules within the virtual resource provider, the plurality of control plane modules for managing the virtual machines; receiving input from the customers to select a custom control plane module to replace at least one of the plurality of control plane modules; determining reputation scores associated with at least the custom control plane module and the plurality of control plane modules, the reputation scores associated with input metrics of the provisioned virtual resources; and mediating requests from the plurality of control plane modules and the custom control plane module using the reputation scores.