Open government data is assumed to be a given by many in the US because our copyright law states that federal government data is not covered by copyright. (The situation in US states can vary, but the federal government's declaration sets the tone.) In other countries the situation is less clear and governments do not have a mandate to make data open. However, the open government data movement has purred on a number of fast-moving activities, many sponsored by governments themselves that encourage citizens to download and use government data.
The UK government has a site, Opening up government, where it not only shares data but encourages people to develop apps that use the data. Apps here can alert you to new building and planning projects in your area, and give you real-time public transportation information.
All Data on dev.govdata.eu is available under a worldwide, royalty-free, non-exclusive license to use, modify, and distribute the datasets in all current and future media and formats for any lawful purpose and that this license does not give you a copyright or other proprietary interest in the datasets.There is a European site for public sector information, the European Public Section Information Platform: Europe's One-Stop Shop on Public Sector Information Re-use. You can search by country and see news and developments relating to public data, much of which is available for re-use. Because many countries for not have an explicit statement in their copyright laws covering government data, one of the important early steps for these jurisdictions is to develop blanket licenses that they can apply to the data. So when you visit the site you see recent news that Norway has developed a license for its government data and is asking for feedback (if you read Norwegian).
To understand the force of this movement, it is said that Albania and Bulgaria are on the verge of opening some government data.
The Obama administration announced its Open Government effort on the first day of his administration.
To the extent practicable and subject to valid restrictions, agencies should publish information online in an open format that can be retrieved, downloaded, indexed, and searched by commonly used web search applications. An open format is one that is platform independent, machine readable, and made available to the public without restrictions that would impede the re-use of that information.Wired has a US-oriented "how-to" wiki on OGD. (Of course, they include in their "how-to" examples MarijuanaLobby.org, being Wired, but it's a good example of the range of utility of OGD. )
Not all data is at the country level, of course, and the movement is reaching into lower levels of government. Paris has an open data portal, while Enschede Netherlands has an open data declaration for its information. In Italy, the government of the Piemonte Region has a website for its open data.
The government open data movement is heavily influenced by grassroots efforts to convince governments that open data is a good thing -- not just for government watchdogs and opposition movements, but for heathy government and strong business. In the UK there is a Working Group on Open Government Data of the Open Knowledge Foundation, an independent not-for-profit that is promoting, as its name says, open knowledge. In Italy there is the wonderfully named "Spaghetti Open Data." Spain has a broad coalition of non-profits that form the "Coalición Pro Acceso." The CKAN web site, which is a general archive of available datasets of all kinds, has OGD under a number of tags, such as "gov". [Just out: Open Government Data video.]
We hear a lot about problems with copyright, with DRM, with information providers who want to lock down their products. Government data covers a huge variety of information types and is often the key information needed for a lot of civic and scientific decision-making. OGD can generate a mountain of new knowledge, and then tell you how high the mountain is.