The building of and use of open source software systems in the public sector sounds promising. There are many interesting aspects to this topic.
The public sector includes local authorities, health boards, police forces, the fire service, primary and secondary education, etc. It can be argued that they share common processes which have supporting software systems, between regions for a common organisation, and to some extent between organisations. For example, human resources departments provides payroll services, a Hospital has numerous data-entry systems to support wards such as surgery and oncology, local authorities have systems to process council tax.