You dont really need to store co-ordinates, one way to'drop' onto a target is to actually create a 'holder' this way the holder has an image in it and the holder can also do things like dragging around the drop target, as you create these holders you could store them into an array so that you have a list of the dropped objects abd also you can iterate through the list and get co-ordinates etc.
http://gumbo.flashhub.net/pagedrop/ - source included
This example creates a container for the dropped image that allows you to manipulate rotation size and position of the image dropped, load some images drag a image onto the main app and see what happens when you hover over it.
This is exactly what I was looking for. Thank you for the quick response and pointing me in the right direction!
Just a quick note the scrolling in the list is broken, I was trying to get cute with an accelerating scroll but never got around to finishing it.