It all started from developer to developer, and now its going from corporate to corporate and now even from government to their other government departments. There is a growing love for Open Source and its wide and clear. To understand things more clearly in a detailed perspective John Carroll recently wrote a series of articles on Open Source, which is interesting and at the same time informative:Why choose open source?
Open source vs. proprietary: Both have advantages
How the software economy is driven by proprietary work
Open Source: Supply and demand