hi Kevin,
welcome to communities.
i did some google around the issue and found some interesting links
http://communities.vmware.com/thread/237062
http://blogs.vmware.com/vapp/2009/07/commandline-ovf-deployments-.html
IBM link http://pic.dhe.ibm.com/infocenter/psappsys/v1r0m0/index.jsp?topic=%2Fcom.ibm.ipas.doc%2FICON%2Ftopics%2Ftsicn_ovafailsproperty.html
from the above link
<snip>Causes
OVA deployment directly to ESX or ESXi is not supported. You must use VMware vCenter Server (VirtualCenter). To verify the server type, use VMware vSphere Client to select the server in the left column. In the right window, above the Summary tab, you check whether the server is VMware ESX/ESXi or VMware vCenter Server.
Resolution -- Install VMware vCenter Server (VirtualCenter) and deploy the OVA file to this VMware vCenter.
</snip>
i suspect you are trying to deploy the OVF by connecting to ESX. Please connect to VC and try the deployment
-Srinivas