In the current climate, internal promotions are a rarity. They say that you should be changing companies roughly every 3 years to ensure you're getting paid what you're worth, as pay raises don't keep up with experience. New responsibilities come quickly while promotions and pay raises come slowly. The number of times I've heard somebody say that they left a job for an immediate 10-30% (or even 50%!) pay raise and reduced responsibilities for even the same job has gotten to the point where I just expect it now.
Like everything else, it varies, but company loyalty is long dead.