With svn revision 965820, we don't have runtime dependency on Spring. XBeanBrokerService doesn't implement ApplicationContextAware and we introduced BrokerContext which should be used to make bean lookups container neutral. Currently there's only SpringBrokerContext implementation that uses ApplicationContext to lookup for the beans. Similar classes can be implemented for other environments, like Blueprint for example.
To enable usage of broker context in Spring environment, you should use something like
<bean id="springContext" class="org.apache.activemq.spring.SpringBrokerContext" />