It is our pleasure to present to you the Proceedings of AIAI 2007, the 4th IFIP Conference on Artificial Intelligence Applications & Innovations being held from 19* till 21'''of September, in Peania, Athens, GREECE. Relying on a solid theoretical background and exploiting the outcomes of exhaustive research efforts, artificial intelligence technology has been widely applied to various areas aiming at the development of intelligent systems that resemble to an extent human thinking and decision-making. These efforts are supported by the ever-expanding abundance of information and computing power. Typical applications of AI include the personalized access and interactivity to multimodal information based on user preferences and semantic concepts and human-machine interface systems utilizing information on the affective state of the user. Also, advancements in AI gave rise to the science of machine learning whose concern is the development of algorithms and techniques that allow computers to learn. The purpose of the 4th IFIP Conference on Artificial Intelligence Applications and Innovations (AIAI) is to bring together researchers, engineers and practitioners interested in the technical advances, business and industrial applications of intelligent systems. AIAI 2007 is focused on providing insights on how AI can be implemented in real world applications.