Open source software is not new stuff for technology geeks but lot of has happened within this domain of information technology where source code is available for any one and every one to make changes. This variation of software development involves a very rational approach which reduces chances of monopolizing in product within a given industry as they case may be in traditional licensing software business model. Linux, apache, MySQL, PHP are considered backbone in software product development under open source category. Since linux is a open source O/S that’s why we have so many variation available each having idea of improvement. Now SAAS or software as a service is comparatively new buzz word which is being coined along with cloud computing, single/multi-tenant architecture, here the fundamental differentiators from marketing perspective is instant start through subscription model, cost saving as software resides in cloud so you save infrastructure cost which incur from purchasing servers, multiple license in case of multiple servers & other implementation cost that happens in case of traditional Enterprise software with client server model.
Open source coupled with SAAS can be a cool combination.