As of JBoss AS 5.0.0 Beta3, the annotations package for such commonly used annotations as @Service and @Management have moved from the org.jboss.annotation.ejb package to the org.jboss.ejb3.annotation package.  Additionally, the annotations have moved from jboss-annotations-ejb3.jar to jboss-ejb3-ext-api.jar which can be found in the client subdirectory.

This change was tracked in JIRA and is documented in the AS5 Installation and Configuration Guide.

You will need to change your code's import statements as well as recompile your @Service beans with the new JAR to have them deploy as they did in AS 4.2.x.

Attached, you'll find an example @Service bean project that demonstrates use of the new package.  It was built with Java 6 against Java 6-compiled libs.