One of the most important roles an IT Organization can provide is the Lifecycle Management or Portfolio Management of their services. This requires a high level of maturity for the organization but is an advanced step in the implementation of an ITIL-based ITSM solution.
By building your ITSM solution around an ITIL-based framework, you can move the IT Organization towards the management of the full service lifecycle. As described in the ITIL V3 Service Strategy book and Service Design book, Service Portfolio Management (SPM) requires 4 steps: define, analyze, approve, and charter.
If you want to research more information about SPM, you can check out an excellent presentation by Pink Elephant. Listen to the recorded program, Practitioner Radio Episode 13. The conversation is on the strategic process of SPM as a critical means for managing and prioritizing the build/run lifecycle of value and how to avoid Legacy Hoarding.
SPM is an ongoing process for a mature IT organization and their ITSM solution. Choosing a solution with built-in ITIL processes is a great place to start.