Just to add to this. I checked on my own D300 last night and meant to report back but forgot. In P, S and A modes, the exposure scale should be visible in the viewfinder and on the top LCD but the exposure indicator will always be centred. In M mode, the indicator can be well off to one side of course depending what you have dialled in. Is this what you're seeing Paul? From your posts it sounds like the exposure meter is missing all together.
Edited to add (and with apologies if you already know this) that the meter goes into hibernate after x number of seconds (dictated by your own selection in the menu). The meter display is not visible when the meter is 'asleep'. To restart the meter you need to press the shutter or other buttons depending on what you have set in the menu. If you simply pick the camera up after it has been resting for a few seconds and press nothing, the meter scale will not be shown.