Since 2003, a new wave of web-based applications, which now go under the name of web 2.0, have been launched with very little investment and have encountered dramatic success in terms of take-up. These applications rely on the concept of the user as a producer: of content (blog, wiki, Flickr), of taste/emotion (Last.fm, de.li.cious), of contacts (MySpace), and of reputation/feedback (eBay, TripAdvisor). The report looks at how these applications are used and can be used in government-related activities. Based on a survey of existing initiatives in the public and private sector, it argues that web 2.0 applications affect both front and back office activities, such as: regulation, cross-agency collaboration, knowledge management, service provision, political participation and transparency, and law enforcement. For each of these domains, it spells out the key implications and analyzes existing cases. Finally, it draws some lessons to be learnt from existing cases, as well as possible policy options for government. Overall, web 2.0 is already used in many areas of government activity, often without the authorisation or even the knowledge of governmental institutions. To start experimenting with these applications appears to be not only potentially beneficial, but probably the safest option for government.