I created an Automator workflow for the shell script "svnRecover" I wrote about in an earlier post. This allows to restore the .svn folders in a Keynote/Pages or similar document that is under Subversion control. For this, you simply select More->Automator->SVN_Recover from the document's context menu (see screenshot). You can download the automator workflow here. To install it, unzip it and copy the workflow document into the folder ~/Library/Workflows/Applications/Finder in your home directory. (You do not need to install the shell script separately; it is included in the Automator workflow.)
Update 2008-09-16: I fixed a bug that could lead to the deletion of all contents of folders with extended privileges.