The org.jboss.ejb3.deployers.Ejb3ClientDeployer attempts to deploy based on the existence of a Main-Class attribute in an archive's META-INF/MANIFEST.MF. This deployment only makes sense for jar archives and for non-.jar archives an IllegalArgumentException is thrown:

2010-04-21 08:44:54,261 DEBUG [org.jboss.ejb3.deployers.Ejb3ClientDeployer] (main) Error during deploy: vfszip:/bin/jboss-5.0.0.GA/server/default/deploy/mydeployment.rar
java.lang.IllegalStateException: Expected either '.jar' or '.jar/' at the end of mydeployment.rar
at org.jboss.ejb3.deployers.Ejb3ClientDeployer.getDeploymentJndiName(Ejb3ClientDeployer.java:214)
at org.jboss.ejb3.deployers.Ejb3ClientDeployer.deploy(Ejb3ClientDeployer.java:104)
at org.jboss.ejb3.deployers.Ejb3ClientDeployer.deploy(Ejb3ClientDeployer.java:61)
at org.jboss.deployers.vfs.spi.deployer.AbstractSimpleVFSRealDeployer.deploy(AbstractSimpleVFSRealDeployer.java:56)
at org.jboss.deployers.spi.deployer.helpers.AbstractSimpleRealDeployer.internalDeploy(AbstractSimpleRealDeployer.java:62)
at org.jboss.deployers.spi.deployer.helpers.AbstractRealDeployer.deploy(AbstractRealDeployer.java:50)
at org.jboss.deployers.plugins.deployers.DeployerWrapper.deploy(DeployerWrapper.java:171)

Instead of throwing such an exception, the deployer should ignore other types of archives such as .rar archives that happen to have a Main-Class attribute defined.