Why does phpsh not show structured information about variables?

Question

I have just installed phpsh shell as described here: http://vocecommunications.com/blog/2010/12/how-to-setup-an-interactive-wordpress-shell/

Normally, the shell should show introspection of returned variables as here:

php> = get_posts(array('posts_per_page'=>1))
array(
   0 => <object #288 of type stdClass> {
    ID => 1,
...

But in my shell doesn't show anything by itself. I need to wrap the returned variable inside var_dump, as shown here:

php> get_posts( array('posts_per_page'=>1 ))

php> var_dump(get_posts( array('posts_per_page'=>1 )))
array(1) {
  [0]=>

Any idea on how to make shell introspect return variables by default?