The problem I ran into when trying to create a Tile Mapping engine was reading data on Windows Phone. Windows Phone will not allow the below namespace so I had to go another route.

using System.Runtime.Serialization.Formatters.Binary;

Windows Phone has a class called TileContainer which allows access to the Phone's Content area.

             try
            {
                Stream path = TitleContainer.OpenStream("Content/Maps/" + map);
                using (BinaryReader br = new BinaryReader(path))
                {
                    for (int x = 0; x < MapWidth; x++)
                    {
                        for (int y = 0; y < MapHeight; y++)
                        {
                            mapCells[x, y] = new MapSquare(
                                br.ReadInt32(), // Background Layer
                                br.ReadInt32(), // Interactive Layer
                                br.ReadInt32(), // Foreground Layer
                                br.ReadString(), // CodeValue
                                br.ReadBoolean()); // Passable
                        }
                    }
                }