For about six months now I have been using this great app on my iPhone4 for planning outdoor photography trips. It is called The Photographer’s Ephemeris and it allows you to figure out when and where the sun will rise and set when shooting landscape or urban images. You can also determine the time and direction of the moonrise and moonset. There are additional features like phases of the moon and % of illumination etc. The TPE for iOS has recently been updated with some improvements. Any outdoor photographer will find this brilliant app very useful.