I have built a namespace, where only my login is allowed to read those pages. Everybody else (including all logged off users) are not allowed to read these pages.
In my case, the namespace is called "privat" (see example page http://www.heinzer.ch/dokuwiki/doku.php?id=privat:start
where you don't have any access).
But in "Recent changes", everybody can see all the existing page names of these privat namespace (see http://www.heinzer.ch/dokuwiki/doku.php?do=recent&id
If somebody has no read access to a certain namespace, all these pages should not be visible in "Recent changes".
In the version I had installed before (2005-07-01), this bug did not exist.