If you are downloading the new Windows 8 Enterprise edition from MSDN or TechNet today (as a Volume License Customer) and plan on adding in your volume license, you can do so without the need for a Key Management Server (KMS). To do so, run a command prompt as Administrator and enter the following:
slmgr.vbs -ipk "PRODUCT KEY HERE"
After, go back into Windows Activation and choose Activate. You’ll be soon on your way to Windows 8 goodness.