Example of using multiple persistence units with Spring?

Issue

• The following BeanCreationException is encountered when deploying my Spring based application:

  2010-08-30 09:49:51,155 ERROR [com.example.SomeBean] Unable to start Spring Context
  org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'aBean' defined in class path resource [META-INF/applicationContext.xml]: Cannot resolve reference to bean 'someDao' while setting bean property 'someDao'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'someDao': Injection of persistence dependencies failed; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No unique bean of type [javax.persistence.EntityManagerFactory] is defined: expected single bean but found 2
      at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:328)
      at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:106)
      ...