Ant 1.8.0 is out and is considered the new stable version.
However, it fails with generated build.xml files, being unable to resolve path references.
Ant 1.7.1 already warned for this, with messages like this:
Warning: Reference saxon.classpath has not been set at runtime, but was found during
build file parsing, attempting to resolve. Future versions of Ant may support
referencing ids defined in non-executed targets.