I just learned a little trick today I thought I’d share. If you want to see all of the folks in your Ancestry.com tree that have new 1940 census hints, there are two ways you can do so relatively painlessly.
Go to one of your saved trees and “View all people with hints.” (You can do this from the ancestry home page, or use the search box drop down list.) Then append the url with the hints?hf=record&hdbid=2442 and enter. You will see the collection filter appear below the “Filter by” options. Thus the full url will look something like this (replace the ####### with your tree number):
Go to http://search.ancestry.com/iexec/?htx=List&dbid=2442 and off to the right you will see “X hints in your Family tree are from the 1940 United States Federal Census.” Underneath this is a link to “View all hints from this Collection.” You can click on it, or if you have multiple family trees, use the “next>” button just below the selection to change trees before viewing all hints.
This is much easier than seeking out individuals one by one to see which 1940 census hints are available.