The cobertura plugin does not generate reports for maven2 based projects. The
problem ist that the cobertura plugin is programmed against a deprecated api.
Take a look at the patch below:

Index: src/main/java/hudson/plugins/cobertura/CoberturaPublisher.java
===================================================================
— src/main/java/hudson/plugins/cobertura/CoberturaPublisher.java (revision 9030)
+++ src/main/java/hudson/plugins/cobertura/CoberturaPublisher.java (working copy)
@@ -186,7 +186,7 @@
/**

• {@inheritDoc}

  */

• public boolean perform(Build<?, ?> build, Launcher launcher, BuildListener
  listener) throws InterruptedException, IOException {
  + public boolean perform(AbstractBuild<?, ?> build, Launcher launcher,
  BuildListener listener) throws InterruptedException, IOException {
  if (!Result.SUCCESS.equals(build.getResult())) { listener.getLogger().println("Skipping Cobertura coverage report as build was not successful..."); return true; @@ -191,8 +191,9 @@ listener.getLogger().println("Skipping Cobertura coverage report as build was not successful..."); return true; }

  +
  listener.getLogger().println("Publishing Cobertura coverage report...");

• final Project<?, ?> project = build.getParent();
  + final Project<?, ?> project = (Project<?, ?>) build.getProject();
  final boolean multipleModuleRoots;
  if (project.getScm() instanceof SubversionSCM) {
  // hack of the first kind