swagProductDetailsView

App.SwagProductDetailsView = App.BaseView.extend({
    cssProperties:['width'],
    _selectedObserver:function(){
        "use strict";
        var show = this.get('current.id') === this.get('item.id');
        var width = show ? '326px' : '0px';
        this.setProperties({ width:width, duration:300 });
    }.observes('current.id','item.id').on('didInsertElement')
});

swagRowController

App.SwagRowController = Em.ObjectController.extend({
    selected:true,
    currentItem:null,
    actions:{
        selectProduct:function(product){
            "use strict";
            this.set('currentItem',product);
        }
    }
});

swagRowProductController

App.SwagRowProductController = Em.ObjectController.extend({
    selected:false,
    inStockLabel:Em.computed(function(){
        "use strict";
        return this.get('inStock') ? 'In Stock' : 'Out of Stock';
    }).property('inStock')
});

template.hbs

 {{#each row in controller itemController="SwagRow"}}
	{{#each item in row.swagProducts itemController="SwagRowProduct"}}
	<div class="swag-item" {{action "selectProduct" item}}>
	    <a class="image">
	  	{{#if row.selected}}
	            <img {{bindAttr src="item.thumbnailLarge"}}>
			{{else}}
	            <img {{bindAttr src="item.thumbnailSmall"}}>
			{{/if}}
	    </a>
	
		{{App.SwagProductDetailsView
			class="swag-item-details"
			itemBinding="item"
			currentBinding="row.currentItem"}}
	{{/each}}
{{/each}}