I was recently tasked with backporting a project that builds in Maven 2 to Maven 1 (odd I know). It was a nightmare of a job.
You get so used to Maven 2 pulling in all the dependencies it needs (transitive dependencies) and doing all the work for you (building the Java source) that you forget how tedious it used to be. ie specifying all of the jars that you need, and all the dependent jars that those jars need.
Anyway, I finally finished it, but with the help of a simple Maven2 command:
which produces the following tree of all your dependencies and dependencies of those dependencies:
Certainly helps tracking down any missing dependencies in your project.xml