This is about IT meeting the service needs of the business by considering areas such as:
- Service level agreements (SLAs)
- Availability (keeping it running)
- Capacity (making sure the service won't struggle to deliver, but isn't over engineered and wasting money)
- Continuity (getting it running again when things go wrong)
For larger organisations, SLAs are usually agreed, measured, and reported against. For medium enterprise, it's often not so much around measurement, but rather about getting things set up right so that you can provide your staff with good IT service, and they can then do their job and make the company money. They'll soon tell you when things aren't going well!
It's important to note that with IT, you don't provide the business with any products, because products are only used to provide a service, and aren't measurable. For example, you don't provide your staff with a network - rather you provide them with a network connectivity service, that should be available x% of the time.
Service delivery is something that can be defined through various frameworks, and it's always best to scale these frameworks to the size of the organisation as they can be incredibly prescriptive and expensive!