One method, of course, is to assert that IT resources are limited and overall demand has to be limited to what's available. An evaluation process that resource requesters (apps groups, in other words) have to undergo to justify resource access could be imposed.

For a variety of reasons, this is unlikely to be successful, not least due to the easy availability of external cloud resources. In a recent workshop attended by middle management trying to figure out the cloud, I demonstrated that Amazon could have a virtual machine up and running in two minutes (it was especially fast that day). Their surprised responses told me how powerful this example was. As the old song goes, "?" One attendee, however, insisted that end user self-service is not necessary and it's still ok to have all requests evaluated and approved by an operations group. I think his career prospects, along with the viability of this strategy, is limited.

This strategy is, in essence, the "if you can't beat 'em, join 'em" approach. All things being equal, application groups will undoubtedly prefer to work with internal groups and internal resources.

Of course, there are several implications to this strategy. The first is that chargeback needs to be in place. This is a fairly controversial subject within cloud computing, with many people asserting that chargeback is not necessary or that "showback" (reporting as to total resource consumption) is sufficient. This seems untenable as an ongoing mode of operation. Price is a very efficient rationing mechanism (certainly more efficient than the process-based rationing outlined above), and being able to demonstrate true pricing vis a vis external providers is table stakes.

The second implication is that the prices need to be fairly competitive with external providers -- maybe not as low, but certainly not five, ten, or twenty times higher. This will require the internal cloud to pare capital and running costs -- and achieve very high utilization rates.