Also, the jar file must have a META-INF/services/java.sql.Driver file.
If the jar does not contain that file, it can be included in the module by adding a jboss-7.0.0.<release>/modules/com/mysql/main/files/META-INF/services/java.sql.Driver and to have the module.xml reference the extra resource root
<module xmlns="urn:jboss:module:1.0" name="com.mysql">
<resources>
<resource-root path="files"/>
<resource-root path="mysql-connector-java-5.1.15.jar"/>
</resources>
<dependencies>
<module name="javax.api"/>
</dependencies>
</module>