We're using the JBoss Seam Scanner class to iterate over all my beans in search for a certain annotation.
To do so we had to create a class within the org.jboss.seam.deployment Java package since the handleItem method is package visible.
This class is packaged in my EJB 3.0 JAR as part of an EAR application.
When deploying the application I get the following exception:

Caused by: java.lang.AbstractMethodError
at org.jboss.seam.deployment.Scanner.handleArchive(Scanner.java:139)
at org.jboss.seam.deployment.Scanner.scan(Scanner.java:118)

The jboss-seam.jar lives in $JBOSS_HOME/server/default/lib. So AFAIK the org.jboss.seam package has two classloaders, one pointing to jboss-seam.jar and the other to my EAR classloader. Could this be the cause of that exception?