Here is a page that demonstrates the problem:
http://bluweb.com/us/chouser/gmapez/test02.html

This page shows two maps created with identical code.  However, only
the second map has it's infoWindow opened correctly (at least in
Firefox).  Here is the code:

    <div id="map1" style="width: 300px; height: 300px"></div>
    <div id="map2" style="width: 300px; height: 300px"></div>
    <script type="text/javascript">
      function openInfo( mapid ) {
        var point = new GPoint(-122.141944, 37.441944);
        var map = new GMap(document.getElementById( mapid ));
        map.centerAndZoom( point, 4 );
        marker = new GMarker( point );
        map.addOverlay( marker );
        marker.openInfoWindowHtml( mapid );
      }

      openInfo( "map1" );
      openInfo( "map2" );
    </script>

You can work around the problem by using a timer to call
openInfoWindowHtml a second later, rather than trying to do them both
on page load.

Has anyone else seen this?  Know of a better work around?  Anyone at
Google willing to fix it?

--Chouser

I now have a workaround for this bug.

For my application, I have added a doOpen() method to each marker which
calls marker.openInfoWindowHtml() with the appropriate HTML for that
marker.  I also have an array autoOpen with a list of the markers I
want to open, each from on a different map.

Here is some code to open all the markers in autoOpen, but only the
last one actually opens because of this bug:

  for( i = 0; i < autoOpen.length; ++i )
    autoOpen[ i ].doOpen();

Here is my workaround:

  function chainOpen( i ) {
    if( i < autoOpen.length ) {
      GEvent.bind( autoOpen[ i ], "infowindowopen", null, function(){
        chainOpen( i + 1 );
      });
      autoOpen[ i ].doOpen();
    }
  };
  chainOpen( 0 );

Pasha, Brett, or any other Googlers watching this group, please see
about fixing this bug for real.

Thanks,
--Chouser

I missed an unintended side-effect of the work-around given above.
Since the chain of event listeners remained, subsequently re-opening
any of the autoOpen markers would also re-open all markers further down
the list.  I think this is better:

  function chainOpen( i ) {
    if( i < autoOpen.length ) {
      var onOpen = GEvent.bind(
          autoOpen[ i ],
          "infowindowopen",
          null,
          function(){
            GEvent.removeListener( onOpen );
            chainOpen( i + 1 );
          });
      autoOpen[ i ].doOpen();
    }
  };
  chainOpen( 0 );

--Chouser