So far, based on testing I think the answer is no. But it seems like a reasonable thing to do.

I created the ear with this structure:

my.ear
 META-INF
 application.xml
 jboss-app.xml
 my.jar
 my.sar
 META-INF
 jboss-service.xml

In the jboss-app.xml i tried both

<module>
 <service>my.sar</service>
 </module>

<module>
 <service>my.sar/</service>
 </module>

The 1st one receives an error that it can not find my.sar.
The 2nd one got farther, but receives an error that the jboss-service.xml can not be found.

I bit the bullet and jared up my.sar and all works well.

BUT, is it possible to deploy an exploded sar inside an ear? Did I do something wrong? Or would this be an exhancement to the EARDeployer?