Lots of talk on the internet around Flat Design and Skeumorphism. Here are some handy links (Thanks Jason!) on the topic.
DesignModo: Skeumorphism in UI Design, What is It?
Cole Peters: Flatliners
John Gruber: The Trend Against Skeuomorphic Textures & Effects in User Interface Design
Max Rudberg: Flat UI is not the only way forward
Matthew Moore Design: Almost Flat Design