"mvn clean install" crashes with java.lang.OutOfMemoryError: PermGen space after update to java 1.6.0_04

After upgrading to java 1.6.0_04 i can't build a big multi-module project anymore.
java.exe keeps allocating more and more memory (ca. 260MB) until it crashes with an error like the following:
Failure executing javac, but could not parse the error:

The system is out of resources.
Consult the following stack trace for details.
java.lang.OutOfMemoryError: PermGen space
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
at java.net.URLClassLoader.access$000(URLClassLoader.java:56)
at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at org.codehaus.plexus.compiler.javac.IsolatedClassLoader.loadClass(IsolatedClassLoader.java:56)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
at com.sun.tools.javac.comp.Annotate.<init>(Annotate.java:52)
at com.sun.tools.javac.comp.Annotate.instance(Annotate.java:36)
at com.sun.tools.javac.jvm.ClassReader.<init>(ClassReader.java:215)
at com.sun.tools.javac.jvm.ClassReader.instance(ClassReader.java:168)
at com.sun.tools.javac.main.JavaCompiler.<init>(JavaCompiler.java:293)
at com.sun.tools.javac.main.JavaCompiler.instance(JavaCompiler.java:72)
at com.sun.tools.javac.main.Main.compile(Main.java:340)
at com.sun.tools.javac.main.Main.compile(Main.java:279)
at com.sun.tools.javac.main.Main.compile(Main.java:270)
at com.sun.tools.javac.Main.compile(Main.java:87)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.codehaus.plexus.compiler.javac.JavacCompiler.compileInProcess(JavacCompiler.java:420)
at org.codehaus.plexus.compiler.javac.JavacCompiler.compile(JavacCompiler.java:141)
at org.apache.maven.plugin.AbstractCompilerMojo.execute(AbstractCompilerMojo.java:493)
at org.apache.maven.plugin.TestCompilerMojo.execute(TestCompilerMojo.java:102)
at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:447)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:539)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLifecycle(DefaultLifecycleExecutor.java:480)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:459)

Executing the same command with this setup
Maven version: 2.0.8
Java version: 1.5.0_13
OS name: "windows xp" version: "5.1" arch: "x86" Family: "windows"
works perfectly. java.exe allocates at most 110MB.

Increasing the PermGen space using -XX:MaxPermSize=512M didn't help, either...

This is probably a java regression introduced with j6u4 but it could also be a problem in org.codehaus.plexus.compiler.javac.IsolatedClassLoader.
I didn't experience any other problems with the new java version, so far.