Photoshop JSX code for getting all the smart objects in a scene, opening them for editing, and saving them out as PNG sprites to folders that match the Photoshop folders they are stored within.

GetAndSaveSmartObjects.jsx

var activeDocName; 
var activeDocExtension; 
var filePath;
var fileName; 

function GetAndSaveSmartObjs() 
{
    $.writeln("GetSmartObjs called...");

    var rootLayers = new Array();
    rootLayers = app.activeDocument.artLayers; //get layers at the root level.
    
    //ROOT LAYERS//////////////////////////////////
     if(rootLayers.length > 0)
    {
        var smartObjs = GetSmartObjsInLayers(rootLayers); //get the smart obs in these layers
        SaveSmartObjs(smartObjs);
    }
    else 
    {
        $.writeln("rootLayers array is empty.");
    }  
    
    //LAYER SETS///////////////////////////////////////////////
    var rootLayerSets =  app.activeDocument.layerSets; //get root layers sets
    
    //get the smart obs in these layer sets.
    for(var i = 0; i < rootLayerSets.length; i++) 
    {
        var layersInSet = rootLayerSets[i].layers;
        var smartObjs = GetSmartObjsInLayers(layersInSet);
        SaveSmartObjs(smartObjs, rootLayerSets[i].name);
    }
 }

function GetSmartObjsInLayers(layers) 
{
    var smartObjs = new Array();
    
    try 
    {
        if(layers.length > 0)
        {
            for(var i = 0; i < layers.length; i++) 
            {
                if(layers[i].kind == LayerKind.SMARTOBJECT) 
                {
                    $.writeln("Adding smart obj: " + layers[i].name);
                    smartObjs.push(layers[i]);
                }
            }
        }
        else 
        {
            $.writeln(layers.name + " array is empty.");
        }
    }
    catch(e)
	{
		alert(e);
		$.writeln(e);
	}
    return smartObjs;
}

function SaveSmartObjs(smartObjsArray) 
{
        SaveSmartObjs(smartObjsArray, null);
}

function SaveSmartObjs(smartObjsArray, folderName) 
{
    try 
    {
        if(smartObjsArray.length > 0)
        {
            for(var i = 0; i < smartObjsArray.length; i++) 
            {
                if(smartObjsArray[i].kind == LayerKind.SMARTOBJECT) 
                {
                     var smartObj = smartObjsArray[i];
                     
                    activeDocName = app.activeDocument.name.replace(/\.[^\.]+$/, ''); 
                    activeDocExtension = decodeURI(app.activeDocument.name).replace(/^.*\./,'');
                    filePath = app.activeDocument.path;		
                    fileName = File(filePath + "/" + activeDocName);
                    var fullFilePath;
                    
                    if(folderName == null) 
                    {
                        fullFilePath = File(filePath + "/" + smartObj.name); 
                    }
                    else 
                    {
                        fullFilePath = File(filePath + "/" + folderName + "/" + smartObj.name);
                        CreateFolder(fullFilePath);
                    }
                
                    $.writeln("fullFilePath: " + fullFilePath);                   
                                       
                    $.writeln("Edit contents of smart obj: " + smartObj.name);

                    //Undocumented code derived from the Photoshop script listener 
                    //it opens the smart object for editing of the contents
                    //which when opened crops the layers to the size of the sprite
                    //this allows us to then saved a PNG that is the correct size for the smart object.
                    app.activeDocument.activeLayer = smartObj; 
                    var idplacedLayerEditContents = stringIDToTypeID( "placedLayerEditContents" );
                    var desc7 = new ActionDescriptor();
                    executeAction( idplacedLayerEditContents, desc7, DialogModes.NO );
                                        
                    SavePNG(fullFilePath);
                    CloseDocument();
                }
            }
        }
        else 
        {
            $.writeln(smartObjsArray.name + " array is empty.");
        }
    }
    catch(e)
	{
		alert(e);
		$.writeln(e);
	}
}

function CreateFolder(fullPath) 
{
    var folder = new Folder(fullPath);

    if ( ! folder.exists ) 
    {
        folder.create()
    }
}

function SavePNG(fullFilePath) //e.g. fullFilePath = "C:/Folder/Texture.psd"
{
	$.writeln("SavePNG(" + fullFilePath + ")");
	try
	{
		if(fullFilePath.exists)
		{
			fullFilePath.remove(); 
		}

		pngSaveOptions = new PNGSaveOptions();
		activeDocument.saveAs(fullFilePath, pngSaveOptions, true, Extension.LOWERCASE);
	}
	catch(e)
	{
		alert(e);
		$.writeln(e);
	}
}

function CloseDocument()
{
	app.activeDocument.close(SaveOptions.DONOTSAVECHANGES);
}

GetAndSaveSmartObjs();