I had to list the host UUID of all the ESXi hosts in an environment recently. This is just a quick post, to show how to grab this information using PowerCLI.
After pointing the PowerCLI session at the relevent vCenter (or ESXi host), run the following:
Get-VMHost | Select Name,@{n="HostUUID";e={$_.ExtensionData.hardware.systeminfo.uuid}}
This results in listing each host, along with its UUID:
Nice and easy!