So you just submitted your app to the Apple's review team. Before starting work on the next release of your app, you should create a tag in your subversion repository to keep a marker of the sources for the submitted release. Simple to do:
svn copy file:///Users/username/Subversion/UPM/trunk/uPasswords file:///Users/username/Subversion/UPM/tags/220.127.116.117 -m "tagging UPM Version 18.104.22.1687"
That is all. Now, in Xcode's Organizer, click the Repository tab then expand the tags node. You'll get all the tags you defined.