The annual Game Developers Conference was held this week, and the iPhone played a big part in the GDC festivities. Many developers were demonstrating their iPhone games, solidifying the iPhone as a gaming platform. In this video, we take a look at five new iPhone games: Star Defense and LiveFire from ngmoco; Space Trader from HermitWorks; Dexter The Game from Marc Ecko Entertainment; and Defend Your Castle from XGen Studios.