Building With Ant + Maven Antlib?

I discovered a new baby in the build world. Some open source projects use a combination of ant and maven. I thought you could vaguely use ant from maven. But I did not know of Maven Antlib that allows you to use maven2 from Ant. Why would you use Maven2 from Ant?

• because Maven2 requires to adapt your project to its standard hierarchy, or to have excellent Maven2 skills to create your own archetype for each existing project.
• because everybody knows Ant, but Ant does not manage dependencies well. Maven2 Antlib can be used just for that: managing dependencies.

I have to try that on a real project to see if it is really an easy and flexible approach, better than plain Maven2.