The product (SKU) document is just like any other document and is getting stored in CMS_Document table (apart from some specific sku fields). As you want to get URL of document you can simply use code which Brenden has suggested. You can also try exploring the CMSContext.CurrentDocument property or CMSContext.CurrentDocument.Parent to find more information about the object. You can e.g. use Parent multiple times.
Let me know if you have further questions.