Thats a bit strange sam. I refer to this link
http://edocs.bea.com/wls/docs70/programming/classloading.html#1029830 and the figure 3-1. What i see is that there is a System Classpath classloader
a Ejb Class Loader
and an Web app classloader
The EJB1 and EJB2 are shown as ifthey coexist withing a single class loader so if they share a utility class for example it should be available to both EJB1 and EJB2.
Another question that comes to my mind is that if EJB1 invokes EJB2 which are in different jars then do the EJB1 jar file need to have the EJB2 Home and remote classes.