The approach that I think is most appropriate for most publicly produced and publicly funded data sets is a well-known license called Creative Commons by attribution. What that means is that other people can take those data and reuse them for their own purposes, but they have to link back to the original producer of the data. In a culture, that means that people will see a data source. They may try to abuse the data, but those data have to link back to their origin, so if they're in network of people and they're trying to spread false or abused information--
On February 14th, 2011. See this statement in context.