AFAIK we only support JDK 1.6 for EAP 5. So the Installation guide should be changed accordingly:

2.1.2. Configuring Your Java Environment
You must have a working installation of JDK 1.5 or JDK 1.6 before you install JBoss Enterprise
Application Platform. You can install the 32-bit or 64-bit JVM as per your requirements. In this guide
we will show you how to install a 32-bit Sun JDK 5.0 using RHN, on a generic Linux Platform and
Microsoft Windows Platform But before we do that let's take a look at some of the benefits of using a
64-bit JVM.

Should be:
You must have a working installation of JDK 1.6 before you install JBoss Enterprise
Application Platform. You can install the 32-bit or 64-bit JVM as per your requirements. In this guide
we will show you how to install a 32-bit Sun JDK 6.0 using RHN, on a generic Linux Platform and
Microsoft Windows Platform But before we do that let's take a look at some of the benefits of using a
64-bit JVM.

Also, the instructions on how to install Sun JDK 5.0 from RHN should be upgraded to installing Sun JDK 6.0 or even OpenJDK 1.6. The same goes for "Installing and Configuring 32-bit Sun JDK 5.0 on a generic Linux platform" and "Installing and Configuring 32-bit Sun JDK 5.0 on Microsoft Windows".