Automatically set 'compare' => 'IN', when meta value is an array

[scribu]

get_posts( array(
  'meta_key' => 'foo',
  'meta_value' => array( 'bar', baz' )
) );

should just work.

Currently, you have to remember to set meta compare:

get_posts( array(
  'meta_key' => 'foo',
  'meta_value' => array( 'bar', baz' ),
  'meta_compare' => 'IN'
) );