If you are using Hibernate with Hazelcast as 2nd level cache provider, you can easily create RegionFactory instances within Spring configuration (by Spring version 3.1). That way it is possible to use same HazelcastInstance as Hibernate L2 cache instance.

<hz:hibernate-region-factory id="regionFactory" instance-ref="instance" />
...
<bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean" scope="singleton">
    <property name="dataSource" ref="dataSource"/>
    <property name="cacheRegionFactory" ref="regionFactory" />
    ...
</bean>