Some very large projects are linking multiple heterogeneous parallel computers together, with high-speed networking in between. This is called Meta-Computing. Doing this requires operator intervention, however, to get the machines scheduled. Meta-schedulers are needed, which communicate with schedulers on each machine. Protocols are needed, as are algorithms to do the scheduling.
Processors are often idle, or are running at a very low fraction of their peak performance.
Since these are very expensive processors, this is costly. We actually know very little about the use of the CPC machines, and it would help to learn more about the efficiency of the programs, what sort of usage patterns there are, etc. Ultimately the goal would be to improve overall utilization.