this will allow me to specify a [[Image:imagename.png]] link to an image that is not stored locally but rather on a shared image folder on wiki A. But does it pull down the image that is linked within an article. When the article comes through on wiki B, it appears that the link to the image is a complete link and not a wiki link. Would it still resolve the $wgshareduploadspath?
According to [[Help:Images]] on Wikipedia, [[Image:imagename.png]] will be turned into the picture with that file name as stored on the local wiki if it exists, if it doesn't exist it will look at the wiki specificed in the sharedupload parameter and use that (if it still doesn't exist, it will be a redlink).