It looks like the tomcat6 snapshot has updated to use an AtomicInteger for the accessCount ivar and invalidated all direct use of this field:
 
/services/cruisecontrol/checkout/jboss-head/tomcat/src/main/org/jboss/web/tomcat/tc6/session/ClusteredSession.java:793: incompatible types
found   : int
required: java.util.concurrent.atomic.AtomicInteger
         accessCount = 0;

From: qa@jboss.com [mailto:qa@jboss.com]
Sent: Wednesday, August 02, 2006 7:48 AM
To: Bill Decoste; jboss-development@lists.jboss.org; Kabir Khan; QA; Scott M Stark; wolfc@jboss.com
Subject: jboss-head-jdk-matrix Build Failed
Importance: High

View results here -> http://cruisecontrol.jboss.com/cc/buildresults/jboss-head-jdk-matrix?log=log20060802101805

BUILD FAILED
Ant Error Message: /services/cruisecontrol/work/scripts/build-jboss-common.xml:287: The following error occurred while executing this line: /services/cruisecontrol/work/scripts/build-jboss-common.xml:62: Exit code: 1 See compile_jdk15.log in Build Artifacts for details.
Date of build: 08/02/2006 10:18:05
Time to build: 29 minutes 27 seconds
Last changed: 08/02/2006 10:01:10
Last log entry: Update the javac sourc/target to 5

 Unit Tests: (0)  Total Errors and Failures: (0)
 

 Modifications since last build:  (first 50 of 40)
55031 modified scott.stark@jboss.org //trunk/system/build.xml Update the javac sourc/target to 5
55030 added wolfc //trunk/ejb3/src/test/org/jboss/ejb3/test/regression/ejbthree670/unit/PreDestroyCallsTestCase.java EJBTHREE-670: unit test
55030 added wolfc //trunk/ejb3/src/test/org/jboss/ejb3/test/regression/ejbthree670/MyStateful.java EJBTHREE-670: unit test
55030 added wolfc //trunk/ejb3/src/test/org/jboss/ejb3/test/regression/ejbthree670/unit EJBTHREE-670: unit test
55030 added wolfc //trunk/ejb3/src/test/org/jboss/ejb3/test/regression/ejbthree670 EJBTHREE-670: unit test
55030 added wolfc //trunk/ejb3/src/test/org/jboss/ejb3/test/regression/ejbthree670/MyStatefulBean.java EJBTHREE-670: unit test
55029 modified wolfc //trunk/ejb3/build-test.xml EJBTHREE-670: unit test
55026 modified kabir.khan@jboss.com //trunk/aop/src/main/org/jboss/aop/classpool/AOPClassPool.java Add toString() method to get some info about the classloader
55025 modified scott.stark@jboss.org //trunk/build/build-distr.xml Remove the default target
55024 modified scott.stark@jboss.org //trunk/system/src/main/org/jboss/Main.java Expose the booted server instance and shutdown.
55023 added scott.stark@jboss.org //trunk/system/src/main/org/jboss/system/server/profile Add the profileservice based server impl
55023 added scott.stark@jboss.org //trunk/system/src/main/org/jboss/system/server/profileservice Add the profileservice based server impl
55022 deleted scott.stark@jboss.org //trunk/system/src/tests/org/jboss/beans/container/support/AbstractBeanContainerTestCase.java Remove the unused bean container tests
55022 deleted scott.stark@jboss.org //trunk/system/src/tests/org/jboss/beans/container/support/ContainerTestSuite.java Remove the unused bean container tests
55022 deleted scott.stark@jboss.org //trunk/system/src/tests/org/jboss/beans/container/support/AbstractMutableBeanContainerTestCase.java Remove the unused bean container tests
55021 modified scott.stark@jboss.org //trunk/system/.project Add a dependency on the test project
55020 modified scott.stark@jboss.org //trunk/system/.classpath Add test output and mc jars
55019 modified scott.stark@jboss.org //trunk/varia/.classpath Remove the codec jar from the classpath
55011 modified bdecoste //trunk/ejb3/src/main/org/jboss/ejb3/security/Ejb3AuthenticationInterceptor.java empty string unauthenticatedPrincipal
55010 added bdecoste //trunk/ejb3/src/resources/test/unauthenticatedprincipal/META-INF/ejb-jar.xml test for <unauthenticated-principal>
55010 added bdecoste //trunk/ejb3/src/resources/test/unauthenticatedprincipal/users.properties test for <unauthenticated-principal>
55010 added bdecoste //trunk/ejb3/src/test/org/jboss/ejb3/test/unauthenticatedprincipal/StatelessBean.java test for <unauthenticated-principal>
55010 added bdecoste //trunk/ejb3/src/test/org/jboss/ejb3/test/unauthenticatedprincipal/unit test for <unauthenticated-principal>
55010 added bdecoste //trunk/ejb3/src/resources/test/unauthenticatedprincipal/META-INF/jboss.xml test for <unauthenticated-principal>
55010 added bdecoste //trunk/ejb3/src/resources/test/unauthenticatedprincipal/roles.properties test for <unauthenticated-principal>
55010 added bdecoste //trunk/ejb3/src/test/org/jboss/ejb3/test/unauthenticatedprincipal test for <unauthenticated-principal>
55010 added bdecoste //trunk/ejb3/src/resources/test/unauthenticatedprincipal test for <unauthenticated-principal>
55010 added bdecoste //trunk/ejb3/src/resources/test/unauthenticatedprincipal/META-INF test for <unauthenticated-principal>
55010 added bdecoste //trunk/ejb3/src/test/org/jboss/ejb3/test/unauthenticatedprincipal/unit/UnauthenticatedPrincipalTestCase.java test for <unauthenticated-principal>
55010 added bdecoste //trunk/ejb3/src/test/org/jboss/ejb3/test/unauthenticatedprincipal/StatelessRemote.java test for <unauthenticated-principal>
55004 added scott.stark@jboss.org //trunk/system/build-test.xml Copy system2 tests to the trunk system project
55003 added scott.stark@jboss.org //trunk/system/src/tests-support Copy system2 tests to the trunk system project
55002 added scott.stark@jboss.org //trunk/system/src/tests Copy system2 tests to the trunk system project
55001 modified scott.stark@jboss.org //trunk/testsuite/src/main/org/jboss/test/xml/XOPUnitTestCase.java Add the required ctor
55000 modified scott.stark@jboss.org //trunk/testsuite/src/main/org/jboss/test/xml/XOPUnitTestCase.java Comment out until jbossxb is updated
54998 modified scott.stark@jboss.org //trunk/testsuite/src/main/org/jboss/test/xml/IntrospectionUnitTestCase.java Comment out until jbossxb is updated
54997 added scott.stark@jboss.org //trunk/system/src/main/org/jboss/deployment/scanner/VFSDeploymentScanner.java Copy the vfs scanner to the trunk system module
54996 added scott.stark@jboss.org //trunk/system/src/main/org/jboss/util Copy the util to the trunk system module until it can be moved to common
54995 added scott.stark@jboss.org //trunk/system/src/main/org/jboss/deployers Copy the vdf deployers to the trunk system module
54994 added scott.stark@jboss.org //trunk/system/src/main/org/jboss/profileservice Copy the profileservice to the trunk system module