Modification
In order to display the date the displayed pages were last modified (rather than the date the article was first added to the category), this extension (1.15-r48711) has been altered on the following lines:
LINE 337 $sSqlSelectFrom = "SELECT page_namespace, page_title, page_id, c1.cl_timestamp FROM $sPageTable"; CHANGE TO: $sSqlSelectFrom = "SELECT page_namespace, page_title, page_id, page_touched, c1.cl_timestamp FROM $sPageTable"; LINE 448 $output .= $wgLang->date($row->cl_timestamp) . wfMsg( 'colon-separator' ); CHANGE TO: $output .= $wgLang->date($row->page_touched) . wfMsg( 'colon-separator' ); OR $output .= $wgLang->timeanddate($row->page_touched) . wfMsg( 'colon-separator' ); The first will display only a date, the second the time and the date.