The blog IT from here has a great post entitled "What is ITSM and should you care?" giving some plain-English insight into the world of ITSM. As tenuous as the term is to define, its benefits are clear: it can reduce downtime in IT and increase overall reliability, reduce IT costs and improve the ROI on technology, and provide cost transparency for better decision making.
The core of the article is about aligning IT with business by making sure IT understands business, not just technology. By meeting the needs of the business, the company can maximize profits and provide the best end-of-line service to customers.
The article suggests one way to maximize ITSM is to make sure all services have an 'owner' - someone within the organization who owns a service and determines its usefulness and/or retirement possibility:
Successful Service Management is built on the partnership between what the business can afford and is willing to invest in and what the business can’t and isn’t. IT should not be making these decisions without the express consent of the business. If you can’t find an owner of a service, consider the radical step of turning it off.
Has your organization assessed all the technology in place to see if it is currently needed / being used / the right fit? If not, your company could be wasting both time and money.