Actually, you can use the Advanced Drive SDK to get whatever metadata of the File object you need, including, for example, the selfLink or the thumbnailLink.
I wrote a GitHub Gist to retrieve thumbnail image URLs from image files we keep stored on Google Drive and automatically insert them as image formulas into a spreadsheet according to a filename pattern based on part numbers from the sheet.
Once you have the URL, you can build an =IMAGE(url) formula with it to insert the image directly into a cell, which may be more useful to you, or you can use the insertImage() function to insert the image into the document as one of those floating overlay things. You can use this same method to fetch a binary blob, if you'd rather insert the image data itself and not just an URL reference to it, but that won't work for formulas (only the overlays using the insertImage() function, blob version). Here's an example from Google Issue 4344 of how to use UrlFetchApp to get an image thumbnail from a file:
function getThumbnail(fileId) {
var file = Drive.Files.get(fileId);
return UrlFetchApp.fetch(file.thumbnailLink).getBlob();
}
If you only want the link, just leave off the getBlob() function. If you want the full size image, try the selfLink property instead. If you want more detail, see my Gist.
This is definitely a workaround, so I don't know if it will continue to work or if Google will finally provide a reasonable implementation in the future. Please note, however, that you need to activate the Drive SDK in your script file under Resources : Advanced Google services and also in the Developers Console. If it doesn't work, make sure the project ID in the Script project matches the one associated with the project in the console. I had to actually create a new project in the console and reset the ID to match in the script.