We upgraded our virtualCenter server 2.5 to vCenter 4 and used one ESX3.5 cluster (existing with VCS2.5) and one vSphere cluster (New server).
Both cluster have his own shared datastore.
But since we upgraded to vCenter, we cannot used the browse datastore option.
Sorry i forget to close this discussion.
Yes you are right, when you upgrade to vCenter 4 the permission some permissions are added for datastore, the permissions added during upgrade is "Datastore\NetworkAccess" that not allow browsing datastore.
We only change this permissions, and all seems to be ok.