Vm's on Datastore created on Shared ISCSI LUN can be vmotion' d. BTW How are you trying to access the LUN from both ESX hosts at the same time ?.
Create a datastore from one of the ESX host ,once done ,just scan the storage adapter on the other ,you should see the newly datastore from the other host as well
We have not yet installed the VC yet, even though we had purchased the enterprise version of ESX we were using it as stand alone as we were waiting for teh SAN box, we have teh VMkernel configured though.
Does Vmmotion needs to be enabled before this and VC installed before the hosts can share the ISCSI LUN.
For Vmotion/migration you need VC server installed. W/o you can share the lun but you can not migrate(hot/cold) any vm.