Located in Hall 7, App Planet was an "event within an event" at last week's Mobile World Congress trade show in Barcelona, Spain. According to the GSM Association, the event was an opportunity to "explore the many dimensions of the dynamic and critically important mobile applications market." The event also stood as an acknowledgement by the organization that applications, especially on smartphones, are quickly becoming critical to the evolution of wireless--as highlighted by the astounding success of Apple's iPhone App Store (over 140,000 apps and counting). The App Planet venue boasted more than 50 app-specific exhibitors in one place. So who was there, and what were they showing? Slideshow