Sun has positioned the StorageTek deal as a way to round out its storage offerings and enhance its status as a total network infrastructure supplier. The strategy absolutely makes sense. It would just make more sense if Sun were acquiring newer disk-based technology of the variety offered by EMC and Network Appliance. It's not that StorageTek doesn't have this stuff; it just isn't the leader. Not by a long shot.
That should tell you that this deal has almost nothing to do with storage, and everything to do with time. That's what StorageTek buys Sun: time.