"Plat_Forms" is a competition in which top-class teams of three programmers compete to implement the same requirements for a web-based system within 30 hours, each team using a different technology platform (Java EE, .NET, PHP, Perl, Python, or Ruby on Rails). The results will provide new insights into the real (rather than purported) pros, cons, and emergent properties of each platform. The evaluation will analyze many aspects of each solution, both external (usability, functionality, reliability, performance, etc.) and internal (structure, understandability, flexibility, etc.).