Crowdsourced geospatial landbase data is competitive in many parts of the world with government or commercial geospatial data. The best known crowdsourced data source is OpenStreetMap. To date OpenStreetMap data has been licenced under Creative Commons (CC-BY-SA 2.0) licensing. But there are some aspects of the CC license that are limiting when used with geospatial data. The two issues with CC licensing I am aware of are distinguishing between collective and derivative work for geospatial data. More often than not, when you're working with geospatial data you are using more than one dataset which represents a collective work. A second motivation is that in some jurisdictions geospatial data is not copyrightable.
For a couple of years a new license, called the Open Database License (ODbL) and specfically tailored for geospatial data, has been under development. OpenStreetMap is moving to the new license on April 1st, 2012. The ODbL license is comprised of an Open Database License (ODbL), a Database Contents License (DbCL) covering the database itself and its contents, and a set of upgraded Contributor Terms covering submissions to the database. Because the ODbL license is replacing CC-BY-SA, everyone who has contributed data to OpenStreetMap will have to explicitly agree to the terms of the new license, which allows OpenStreetMap to distribute his/her data after April 1. Data submitted by folks who don't agree to the new license will be removed from the database after that date.