The Apache Software Foundation has released of Maven 2.0.1, an open source build tool for Java that's more declarative and less procedural than Ant. 2.0.1 is primarily a maintenance release. There've been a lot of problems reported with Maven 2 so far, including one apparently affecting XOM and Jaxen I don't yet fully understand. I'd stay with Maven 1.0 for now until all the kinks get worked out.