$(document).ready(function(){

  var user = 'Benutzername';
  $('form#user-login-form #edit-name').val(user);
  $('form#user-login-form #edit-name').focus(function(){if ($(this).val()==user) $(this).val('');});
  $('form#user-login-form #edit-name').blur(function(){if ($(this).val()=='') $(this).val(user);});

  var pass = 'Passwort';
  $('form#user-login-form #edit-pass').val(pass);
  $('form#user-login-form #edit-pass').focus(function(){if ($(this).val()==pass) $(this).val('');});
  $('form#user-login-form #edit-pass').blur(function(){if ($(this).val()=='') $(this).val(pass);});

  $('form#user-login-form #edit-submit').keypress(function(e){if (e.which == 13) $('form#user-login-form').submit();});

});