We've a simple two node cluster running version 1.5. I've installed version 3.2 on another node.
I'm using this link as a guide. http://pve.proxmox.com/wiki/Proxmox_VE_Cluster
I'm planning on migrating the vm's (all are openvz containers) from 1.5 to 3.2 and then upgrading the 1.5 nodes to 3.2...