Javascript object using "this"

Javascript object using "this"

I'm learning javascript. I want to try creating a simple object for
hiding/showing some blocks of text, so I wrote this code.
var Post = {
init: function(el){
this.el = el;
this.title = el.children(".title");
this.entry = el.children(".entry");
var that = this;
this.title.on("click", function(){
that.hide();
});
},
hide: function(){
this.entry.slideUp('fast');
},
show: function(){
this.entry.slideDown('fast');
}
}
$(".post").each(function(){
Post.init($(this));
})
http://jsfiddle.net/ZVpau/
And the problem is, that this code is always hiding only last post, no
matter what title you have clicked on. Can anyone tell me where is the
problem?