The Apache Logging Services Project creates and maintains open-source software related to the logging of application behavior and released at no charge to the public.
The products of the Apache Logging Services Project include:
Apache log4j 2.0 is a development effort, currently in its infancy, for a log4j designed for Java 5 and concurrency. Design principles, requirements and other development suggestions are collected in the project issue tracker. Development discussion occurs on the log4j-dev mailing list.
Experimental source can be checked out using Subversion:
svn co http://svn.apache.org/repos/asf/logging/log4j/branches/BRANCH_2_0_EXPERIMENTAL