Version 1.4 of the svn diff command will have a "--summarize" option, but previous svn diff doesn't have an option to do this.
If you only are interested in the diffs between, say, revision 10 and the revision just before it: svn log -vq -r10 does exactly what you want. Otherwise, if you're using Unix, this works for any range of revisions: svn log -vq -r123:456 | egrep '^ {3}[ADMR] ' | cut -c6- | sort | uniq.