To get the latest development of Apache Clerezza, you can check out the Source Code and building Clerezza yourself:
svn co http://svn.apache.org/repos/asf/incubator/clerezza/
Additionally, the snapshots below are available for download. Click on the link and download the latest launcher from the list (file which ends with ".jar", e.g. org.apache.clerezza.platform.launcher.tdb-0.5-incubating-20110126.160353-161.jar).
All Clerezza builds are available in the Maven Repository and distributed under the terms of The Apache Software License (version 2.0).