The JS shouldn't affect any elements and the site should render perfectly even without JS enabled, so I can't see it being a jQuery issue!
Try another browser and see if it works?
Update: When taking a look at the page I've only just noticed the tooltips that show the post count and username, it looks like you could be right about the jQuery not displaying it correctly. *disables JS*
Update 2: When disabling JS, the customised tooltip just shows as a generic title attribute tooltip would... looks like this issue might not be JS-related after all.