Service designers are strongly encouraged to clarify the licencing of all of data, and to use an appropriate Creative Commons licence, ideally one that places some or all of the data into the public domain. Recognising that individual users may want alternative licencing details associated with their data, either more or less restrictive than that of the service itself, designers should consider allowing users to select an appropriate Creative Commons licence that can be stored referenced from their data.

As more web services appear and begin to be composed to create other applications, clear licencing of both services and data will become increasingly important.

from Connecting Social Content Services using FOAF, RDF and REST

Via In Search of OU 2.0... Exploring the potential of Web 2.0 techniques and applications in higher and distance education, informal and lifelong learning.