The Open Database License is

The Open Database Licence (ODbL) is a licence agreement intended to allow you to freely share, modify, and use this Database while maintaining this same freedom for others. Many databases are covered by copyright, and therefore this document licenses these rights. Some jurisdictions, mainly in Europe, have specific rights that cover databases, and so the ODbL addresses these rights, too. Finally, the ODbL is also an agreement in contract for you to act in certain ways in return for accessing this Database. (okfn blog)

Here is a clip from the latest Open Knowledge Foundation Newsletter (No. 10) concerning the developments in the Open Database License:

BETA VERSION OF THE OPEN DATABASE LICENSE (ODBL)
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As we announced in January the OKF has adopted the Open Data Commons
project. As part of the project Jordan Hatcher has been working on a
new Open Database License (ODbL) – which is now in beta.

Beta version of the Open Database Licence (ODbL)
http://blog.okfn.org/2009/03/16/beta-version-of-open-database-licence-odbl/

Open Database Licence (ODbL)
http://www.opendatacommons.org/licenses/odbl/

Comments on the license can be made here http://www.co-ment.net/text/844/