An example of non-ironic iris shot as part of the grammar of film is found in "Life Lessons", the Martin Scorsese-directed segment of New York Stories.
In some cartoons and live-action films (and certain television shows like The King of Queens and Mike & Molly), iris shots are used as a way to break the fourth wall, usually for comedic purposes or to allow characters to interact with the audience (as opposed to a simple fade out or cut to an end).
In rare cases, the iris stays closed to a fixed point for the entire shot.
In The Truman Show (Paramount, 1998), for instance, shots are presented as from hidden cameras positioned in small objects such as buttons on shirts.
Gun Barrel Sequence - A similar visual signature used to iconic effect in the James Bond film series.