<ul id="listid" data-role="listview" data-filter="true" data-iconpos="center" data-split-icon="arrow-u" data-theme="c" data-split-theme="b" data-inset="true">
<li><a href="#" id="link1">
  <h2>Title</h2>
  <p>Here is some item<br />with several lines<br />
    <span id="comment1">And this line is supposed to be editable</span>
    <textarea style='display: none; width: 95%;' id="textarea1"></textarea>
   </p></a>
  <a href="#" onclick="alert('Something else happens here')">This does something else</a>
</li>
</ul>

window.toggled = false;

$("#link1").click( function(e){
    var textarea = $("#textarea1").toggle();
    var comment =  $("#comment1").toggle();
    if(window.toggled){
        comment.html(textarea.val());
    }
    else{
       textarea.val(comment.html());
    }
    toggled = !toggled;
});

$("#textarea1").click(function(e){
    if(console && console.log){ console.log(e);}
    e.stopPropagation();
});

<a href="#" id="link1">
<h2>Title</h2>
<p>Here is some item<br />with several lines<br />
<span id="comment1">And this line is supposed to be editable</span>
</p>
</a>
<textarea style='display: none; width: 95%;' id="textarea1"></textarea>