The new licensing model of ArcGIS 10 is designed to prevent duplication of licenses when systems are deployed by way of using drive imaging and virtual machine software. 'Concurrent Use' licensing is the best method to use to ensure ArcGIS 10 systems continues to operate after being deployed as virtual machines.
Prior to imaging or copying a virtual machine, use the ArcGIS Desktop Administrator to point the software to a License Manager serving 'Concurrent Use' licenses. In this way, once a system is duplicated or a drive image is deployed, the new system will query the same license manager for a license.
For more information and alternative deployment models, refer to License Manager Guide: Enterprise deployment of the ArcGIS Desktop or ArcGIS Engine licenses.