When the Free Software Foundation's GNU General Public License v3 was being written, a lot of the discussion centered around what has come to be known as the ASP loophole, through which many Web services providers are able to use open source software without publishing their changes under the GPL because they technically don't "distribute" their software -- they just make it available for use.
On Monday, the Free Software Foundation published the Affero General Public License v3. The AGPL v3 is based on GPL v3, but has "an additional term to allow users who interact with the licensed software over a network to receive the source for that program." According to the Free Software Foundation Web site:
...[A] user can modify [GPL'ed] software and run the modified version on a network server without releasing it. Since use of the server does not imply that people can download a copy of the program, this means the modifications may never be released. Many programmers choose to use the GNU GPL to cultivate community development; if many of the modifications developed by the programs users are never released, this can be discouraging for them. The GNU AGPL addresses their concerns. The FSF recommends that people consider using the GNU AGPL for any software which will commonly be run over a network.
The FSF published the first draft of the AGPL in June and a second draft in August, and in the interim received feedback from the community via the Web. The final draft is published here.