There are two build jobs using OpenJDK. JBAS-9059 issue was fixed but issues still remain trying to build with OpenJDK. I've confirmed with Hudson team that the same version of OpenJDK is used on both systems:

Fedora:
[hudson@vmg12 ~]$ java -version
java version "1.6.0_17"
OpenJDK Runtime Environment (IcedTea6 1.7.1) (fedora-37.b17.fc13-x86_64)
OpenJDK 64-Bit Server VM (build 14.0-b16, mixed mode)

RHEL 5 :
[hudson@conf2 ~]$ /usr/lib/jvm/java-openjdk/bin/java -version
java version "1.6.0_17"
OpenJDK Runtime Environment (IcedTea6 1.7.10) (rhel-1.20.b17.el5-i386)
OpenJDK Server VM (build 14.0-b16, mixed mode)

but the build fails differently. On
RHEL 5/ OpenJDK 1.6.0_17:
ERROR] Failed to execute goal org.apache.maven.plugins:maven-antrun-plugin:1.4:run (build-dist) on project jboss-as-build: An Ant BuildException has occured: The following error occurred while executing this line:
[ERROR] /qa/services/hudson/hudson_workspace/workspace/JBoss-AS-7.0.x-testSuite-openjdk/build/build.xml:72: The following error occurred while executing this line:
[ERROR] /qa/services/hudson/hudson_workspace/workspace/JBoss-AS-7.0.x-testSuite-openjdk/build/lib.xml:42: Unable to create javax script engine for javascript
[ERROR] -> [Help 1]

Fedora 13 / OpenJDK 1.6.0_17 fails with a compilation error:
INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR :
[INFO] -------------------------------------------------------------
[ERROR] /mnt/hudson_workspace/workspace/JBoss-AS-7.0.x-Fedora13/ee/src/main/java/org/jboss/as/ee/beanvalidation/LazyValidatorFactory.java:[92,78] incompatible types; inferred type argument(s) java.lang.Object do not conform to bounds of type variable(s) T
found : <T>javax.validation.bootstrap.ProviderSpecificBootstrap<T>
required: java.lang.Object

Hudson jobs are here:
http://hudson.jboss.org/hudson/job/JBoss-AS-7.0.x-testSuite-openjdk/
http://hudson.jboss.org/hudson/job/JBoss-AS-7.0.x-Fedora13/