I have always thought it is a bit pointless showing the wishlist box all the time, generally because the feature is only available to logged in users, so if you have people browsing the site it is just a empty box
so to make it visible to only customers who have a account and are logged in edit blockwishlist.tpl in you modules/wishlist directory
Just wrap the whole block with the following code
{if logged}
{/if}
simply and then the block only appear when the user is logged in
