VMWare vSphere 4 offers a new Fault Tolerance system that ...
VMware Fault Tolerance, based on vLockstep technology, provides zero downtime, zero data loss continuous availability for your applications, without the cost and complexity of traditional hardware or software clustering solutions
Is this the answer for the SMB that wants relaible servers? Assuming we have a SAN, two compatible servers, and the cash for the VMWare licenses -- is there any downside to VMware FT? Why wouldn't everyone be running FT?