I was under the impression that a partitioned instance used the same IP for each partition. We are currently on a dedicated IP and we are considering using workspaces and partitions for our various business units. I assumed that all of the email we send out would still be from our dedicated IP, but wanted to ask here to confirm.
Yes, you are correct, as soon as you are on a dedicated IP, this IP is shared through all your workspaces. You could purchase multiple dedicated IP's though
If you purchase multiple IPs, you will have the option to name them, so name them clearly by WS or another method.
Then, you have to train marketers and update assets within each workspace to look ONLY at the intended IP and domain. The IPs will cross all Workspaces just like a single IP.