There are plans to relicense the data in OpenStreetMap. So far CC-BY-SA 2.0 is used, but actually it is not the best solution, as the CreativeCommons license does not apply to databases, but to work protected by copyright law.
The OpenStreetMap Foundation has pushed the work on a new license, the Open Database License Agreement (ODbL), developed by Open Data Commons. It is not yet available in a final version, but after reading the available draft, I am convinced, that this license fits the needs of OSM and also my personal wishes.
There is a list of open issues which will hopefully be clarified before the license is released.