If you are talking about sharing HostA's local datastore [datastore1] with HostB's [datastore2], then it might not be possible at least in 4.X release. From 5.0, you can have Xvmotion, so that the VMs are migrated between different hosts of no shared storage.
Again, if you are talking about NAS or FC or iSCSI, then it would be quite the easy method.