Hello Cisco,
I think there is an error about VCenter compatiblity in the n1v compatiblity document for version 1.5.2 and 1.5.2b.
Both versions support ESXi5.1, but in the section "VMware Version Compatibility" the only supported Vcenter versions are 4.1 and 5.0. But VMware supports ESXi5.1 with VCenter 5.1 only. So when 1.5.2 + 1.5.2b want to support vsphere5.1 they must be support also vcenter 5.1, otherwise it makes no sense.
Would be great to get some clarification about it.
Regards Hendrik