> db.set.update({}, {$push : {a : {$each : [{"title" : "x", "rating" : 6}, {title:"y", "rating" : 3}, {title:"z", rating:10}]}}}, true)
> db.set.update({}, {"$push" : {"a" : {"$sort" : {"a.rating" : 1}}}})
> db.set.find().pretty()
{
        "_id" : ObjectId("512b8e6dae74c67969e404cc"),
        "a" : [
                {
                        "title" : "x",
                        "rating" : 6
                },
                {
                        "title" : "y",
                        "rating" : 3
                },
                {
                        "title" : "z",
                        "rating" : 10
                },
                {
                        "$sort" : {
                                "a.rating" : 1
                        }
                }
        ]
}