Object Declaration Question?

Below are some over simplified examples of code the create a single
instance of an object and I was hoping some one could give me the pros
and cons of each approach.

First declaration: In this case a single object is created using object
literal notation and both the get and __Private methods are availabile
for use and no closure is created.

ABC.Util.SomeObject =
{
get : function(val)
{
return this.__Private(val);
},

__Private : function(val)
{
return "testing";
}
}

Second declaration: In this case a single object is create and only the
get function is availabile for use and a closure is created.

ABC.Util.SomeObject = function()
{
var __Private : function(val)
{
return "testing";
}

return {
get : function(val)
{
return __Private(val);
}
};
}();