Yes it's a career. Let's start from the bottom of the ladder:
- You start as a Project Manager Assistant (which is more or less a secretary to the project manager)
- You then start doing some scheduling tasks on your own, so you will become a Project Scheduler.
- After this, you are promoted to a Project Coordinator position
- Once you're a project coordinator, you project manager will feel that you can be of further help to him, so he'll promote you to an Assistant Project Manager.
- After becoming an Assistant Project Manager, the company realizes that you have all the skills to be a project manager, but they want to be sure first, so they promote you to a Junior Project Manager.
- Once you've proven yourself as a Junior PM, it's time to become the real thing, so you now become a Project Manager.
- After managing projects for a few years, the company decides that you're experienced enough to become a senior Project Manager.
- Senior project managers tend to manage multiple projects and multiple project managers, so they are, in one way, gaining the experience to become Program Managers. So, in a few years, you'll become a Program Manager.
- The Program Manager position is an executive position, and you will be managing one or more programs in your company. When the top executives feel that you are now very experienced in program management, they'll promote you to a senior Program Manager position if the position exists, and if it's not already filled. As a senior Program Manager, you'll manage many programs and other program managers will report to you.
- From here, and as the answer below states, the sky is the limit, as you will be promoted to a top management position in the company (such as CTO, CIO, CFO, CEO, etc...)
So again, yes, PM is a career, and a very good one!