I thought I should share this great find:
http://www.canlinkit.com/download
So, you make a child workfile, add some contents to it, save it.
Then you create a parent workfile, import the child workfile as a smart object with CanLinkIt - and then anytime there’s been a change to the child workfile you can just update your sub-version software and then click the “update” button inside the CanLinkIt -panel. Great if you for some reason need to make your PSD modular, so that several artists can work on the same file.