Making sense of the Virtualization Security Players (Updated)

The known virtualization security vendors Reflex Systems, Catbird Security, Altor Networks, HyTrust, Symantec, Trend Microsystems, Tripwire, and VMware all showed their wares at VMworld. Even Checkpoint was showing off their firewall integration within the virtualized environment. Are these really competing products or products that have unique uses within the virtual environment with just a bit of overlap?