The VMware vStorage API mode can be used for VMware vSphere 4 (including ESX/ESXi), vCenter Server 4, VMware Virtual Infrastructure (ESX/ESXi 3.5 and VirtualCenter 2.5)
I have ESX 3.5 u2 + VBR 3.1 and i want to migrate to VBR4. But i don't see any mention of how to install VStorage API! Is it embeded in VBR 4.1?