I am always looking for this command.
Usually, you if you need a code base without the .svn directories, you can just do an svn export. This is especially good for deploying to web applications from known revisions/releases inside of version control.
Sometimes however, there arises the situation where a collection of files that were once in version control, and were orphaned for whatever reason, and that code needs to get re-added to version control, the .svn directories present in the directories will conflict with a new svn add command. In that case use this command:
find . -name .svn -print0 | xargs -0 rm -rf