Note: This site is using Pangolin 1.2.2 beta, which adds more controls to the top pallet.

Here an image logo is placed via custom css as a background image in the top pallet. I'm using the ttg_pallet_top_title phplugins hook to replace the regular Backlight title in the top pallet. I've added the class "logo" to the list item.

Custom css was also needed to remove margin from a list item as well as place the background image, set the list item width to contain the image, and to set the list item to the height of the top pallet.

Here's the phplugins code:

function ttg_pallet_top_title( $style, $path ) { 
  echo '

  <li class="top-pallet-logo"><a href="http://yoursite.com"></a></li>

  ';
  return false;
} // END

Here's the custom css:

 .page__pallet__top > .content > ul > li {
    margin: 0;
    height: 48px;
}

/*logo as background image*/

.top-pallet-logo {
    background-image: url("/backlight/designer/?c=page&a=image&p1=8");
    background-repeat: no-repeat;
    width: 192px;
    height: 48px;
}
li.top-pallet-logo a {
    display: block;
    width: 100%;
    height: 100%;
    }

Of course, use your own background image url and width settings. For this example, I've uploaded the logo image via the Backlight uploader.