Hi Matthieu,
This is certainly doable, but would require adding a bit of javascript code to the main.js file. Specifically, you would have to alter the showDetails function found around line 1153. First, add an attribute (that is a url to the image of the logo(s) you are interested in displaying in the details panel) to each feature in your data. Then, use similar code to:
var logoDiv = $('<img src="'+graphic.attributes.getValueCI(FIELDNAME_LOGOURL)+'">');
var logoFrame = $('<div class="logoFrame"></div>');
$(logoFrame).append(logoDiv);
$(leftDiv).append(logoFrame);
and place it after line 1182 (after the website info is appended to the leftDiv).
You will have to add whatever css rules you will want to apply in the style.css file to achieve your desired look and feel.
-Mark