In working on a project, I created a simple utility class that has this public static method. This basically takes a DisplayObject, copies it, and adds it to a new Sprite which is then returned to the caller. Simple enough. I'm sure this can be refined or done a different way, so have at it.

public static function duplicateImageAsSprite( original:DisplayObject ):Sprite
{
    var bitmapData:BitmapData = new BitmapData( original.width , original.height ,
        true , 0x000000 );
    bitmapData.draw( original as IBitmapDrawable );

    var bitmap:Bitmap = new Bitmap( bitmapData );

    var returnSprite:Sprite = new Sprite();
    returnSprite.addChild( bitmap as DisplayObject );

    return returnSprite;
}