http://gant.codehaus.org/

Gant is just a lightweight façade on Groovy's AntBuilder. It just a way of scripting Ant tasks using Groovy. Gant can be used to do build tasks (see above about "eating its own dog food"), but it doesn't have the integrated artefact dependency management, project lifecycle management, and multi-module/sub-project support that a fully fledged build framework should provide. Gradle on the other hand is a complete build framework based on Groovy and Ivy. If you just want to do some Ant task scripting then Gant is probably the tool you need, but for replacing Ant and Maven as build frameworks (so as to get rid of all the XML and use Groovy), then you probably need to consider Gradle.