Within current context, Enterprise Application Interoperability needs is growing due globalization, virtualization of enterprises and systematic usage of computers aided activities. Leading to emergence of complex ecosystems, such context leads to the necessity of defining and governing standards, which are providing formal and open specifications of components that can be easily assembled to build complete functional solutions. Open standards are nevertheless insufficient in order to ensure pragmatic interoperability. This paper describes the important role of Free Open Source Software (FLOSS) as Enterprise Application Interoperability enabler within the approach we propose in order to produce innovative Frameworks for Enterprise Applications pragmatic interoperability supporting collaboration in the Virtual Enterprise.