I use Lightroom on my desktop all the time to process and categorize my images. Having Lightroom Mobile on my iPhone and iPad makes my collections available wherever I am. I sync my portfolio so that I can show prospective clients my work no matter where we meet to discuss a possible project. If you use Lightroom, you have to get Lightroom Mobile. It is that good!
Carl 56 about Adobe Photoshop Lightroom for iPhone