gistfile1.txt

<div class="tab" id="main">
  <a href="http://yadda.ya/foo#main">Main</a>
  ...
</div>
<div class="tab" id="other">
  a href="http://yadda.ya/foo#other">Other</a>
  ...
</div>
.. etc ..

function switch_to_tab()
{
  var hash = document.location.hash;
  var name = (typeof hash == 'string') ? hash.gsub('#', '') : '';
  
  if(name == '') return;

  $$('.tab').each(function(tab) {
    if(tab.id == name)
      tab.show();
    } else {
      tab.hide();
    }
  }
}

document.observe('dom:loaded', switch_to_tab);