LayerToSprites.Js

// Put this file in Program Files\Adobe\Photoshop\Presets\Scripts\
// In PhotoShop menu File > Automate > Scripts: layersToSprite.js

// Arrange layers into a sprite sheet. 

if (documents.length > 0) 
{
	
	// --------------------------
	docRef = activeDocument;    
	var activeLayer = docRef.activeLayer;

	numLayers = docRef.artLayers.length; 	
	var cols = docRef.width;
	
 	var spriteX = docRef.width;
	var spriteY = docRef.height;
	
	
 	
	// put things in order
	app.preferences.rulerUnits = Units.PIXELS;
	
	//Definir tamanho do Canvas
	
	sqrtLayer =Math.sqrt(numLayers);
	
	newXLeng=Math.ceil(sqrtLayer);
	newYLeng=Math.ceil(sqrtLayer);
	Fit=1;
	
	for (i=0; i < sqrtLayer+1; i++)
 	{ 	
 		if((newYLeng*newXLeng)!= numLayers){
			
			newYLeng=newYLeng-1;	
			Fit=1;
		}
 		else{
			
			Fit=0;
		}
  	}
	if(Fit==1){
		newYLeng = 1;
		alert(newYLeng);
		newXLeng = numLayers;
		alert(newXLeng);
	}
 
 	docRef.resizeCanvas( newXLeng*spriteX, newYLeng*spriteY, AnchorPosition.TOPLEFT );
 	 	
	// move the layers around, j representa Y e i representa X
	NumeroCamada=0;
	
	for(j=0;j<newYLeng;j++)
	{
		
		for (i=0; i < newXLeng; i++)		
 	{ 	   
 		docRef.artLayers[NumeroCamada].visible = 1;
 		
  		var movX = spriteX*i;
		var movY = spriteY *j;
  		
	docRef.artLayers[NumeroCamada].translate(movX, movY);
		
 		NumeroCamada++;
  	}
	}
 	
}	

Sweet !