In many cases, the ITIL community is firmly responsible for this misconception. Asked to describe their ITIL adoption and good practices, they inevitably point to Service Desks, Incident and Problem Management processes, and occasionally Change Management or a CMS tool implementation (often without an underlying CM process to drive its use or efficacy).
With ITIL v3, we have a chance to fundamentally reset everyone's expectations of ITIL. We now acknowledge the whole Service Lifecycle, beginning with Strategy. It's reasonably easy to see the parallels of the activities of Service Strategy and Service Portfolio Management with a PMO; look at business cases, assess ROI and VOI, and approve and charter projects. Likewise, Service Design and Transition provide clear processes and guidance for managing the tactical aspects of capturing functional, nonfunctional, and usability requirements (think utility and warranty), performing service and measurement design, developing or acquiring applications, infrastructure, and metrics management tools, coordinating testing and validation, and overseeing transition planning and execution and operations uptake. These are the fundamental parts of planning and executing any good IT project, and would look very familiar to a PMP. By the way, these models work brilliantly in agile development models as well as more traditional waterfall approaches (which don't work, but that's a different post).
The biggest risk we have for successful ITIL adoption is that very often senior IT management really has no idea what ITIL really is. They think in terms of the most basic Service Operation processes, the Service Desk function, or maybe Change Management, but generally have absolutely no idea how ITIL helps to bridge the yawning cultural chasm in many organizations between Development and Operations. When we teach that Management Commitment is a mandatory critical success factor for ITIL implementation, it begins with basic understanding and clarity of vision across the Service Lifecycle.