title: markerclusterer check if marker is in cluster
body: <p>I have a web based map that is using the <a href="http://code.google.com/p/jquery-ui-map/" rel="noreferrer">jquery-ui-map</a> and <a href="http://google-maps-utility-library-v3.googlecode.com/svn/trunk/markerclusterer/docs/reference.html" rel="noreferrer">markerclusterer</a> plugin to make a google map.</p>
  
  <p>I filter out which markers should be shown or not then update the map.</p>
  
  <p>I need to create a list of unclustered markers and so to this end need a way to check clusters against markers and find out which are not clustered.</p>
  
  <p>Is there any techniques to do this?</p>
  
  <p>I have tried to cycle through clusters and manually check the markers against clusters but get an error telling me the clusters property <code>var_clusterer.clusters_</code> is not defined.</p>