In that sense, yes.
The servlet app is the user interface to the EJBs.
I'm guessing that you're going to have issues unless you're running a servlet container under JDK1.5x. Not sure if the servlet classes themselves would need to be compiled under 1.5.
There are some similar issues going on with
Tomcat right now.
Version 5.5 requires JDK1.5x and servlets compiled under 1.5 can use the new 1.5 features such as the new for loops but these things will not work in
JSP scriptlets because the compiler that ships with Tomcat (Eclipse's JDT) isn't fully 1.5 compliant yet and doesn't understand them.