No, your not missing anything obvious as far as I can see.
That article is from 2008. 11.04 doesnt use ".recently-used.xbel", user actions are now logged by "gnome Zeitgeist". I'd be temped to just remove zeitgeist, who wants (or needs) some stupid spyware file collecting all your actions? Its crap like that that made me distrust microsoft..
Anyway, some directions for how to clear the recent documents in 11.04 are found here-