With the announcement of vSphere 6.0, one very cool feature that is new is Multi-Processor Fault Tolerance. You can now turn FT on for VMs with up to 4 vCPUs. This now opens up Fault-Tolerance to a much larger host of VM workloads. Previously the single vCPU limit excluded almost all server type workload. Update: Doing vCenter FT will be supported in a few limited cases, this is still being worked out by VMware.
To set it up, it is exactly the same as it has been. First, ensure that you have a VMKernel NIC configured for Fault-Tolerant traffic. Then, right-Click on a VM and choose “Turn on Fault Tolerance”. Then choose the location for the Files and then choose a ESXi host that will host the secondary VM, that simple.
One thing to keep in mind is the networking requirements. Since the CPU instructions are being mirrored between the hosts there can be a quite a bit of Network traffic. I have already seen that a 4x vCPU VM can start to consume a pretty good amount of network traffic. I would absolutely have at least a 10gb link dedicated for this purpose.