I've just upgraded my 3.2 install to 3.3. I'm also using Crowd integration and properly followed the instructions.

The upgrade process went smoothly, but after that, Confluence was failing to start, with the following error:

2010-07-08 07:10:29,839 ERROR [Spring executor 1] [plugin.osgi.factory.OsgiPlugin] onSpringContextFailed Unable to start the Spring context for plugin com.atlassian.confluence.plugins.confluence-sal-plugin
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'authenticationController' defined in URL [bundle://29.0:0/META-INF/spring/atlassian-plugins-components.xml]: Instantiation of bean failed; nested exc
eption is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.atlassian.sal.core.auth.SeraphAuthenticationController]: Constructor threw exception; nested exception is java.lang.RuntimeException: C
ould not load security config 'seraph-config.xml': Exception configuring from 'seraph-config.xml : com.atlassian.seraph.config.ConfigurationException: Could not getRequest service: com.atlassian.confluence.user.ConfluenceLoginInterceptor
: java.lang.ClassNotFoundException: com.atlassian.confluence.user.ConfluenceLoginInterceptor
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:883)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:839)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:440)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory$1.run(AbstractAutowireCapableBeanFactory.java:409)
at java.security.AccessController.doPrivileged(Native Method)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:380)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:264)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:261)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:185)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:164)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:429)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:728)
at org.springframework.osgi.context.support.AbstractDelegatedExecutionApplicationContext.access$1600(AbstractDelegatedExecutionApplicationContext.java:69)
at org.springframework.osgi.context.support.AbstractDelegatedExecutionApplicationContext$4.run(AbstractDelegatedExecutionApplicationContext.java:355)
at org.springframework.osgi.util.internal.PrivilegedUtils.executeWithCustomTCCL(PrivilegedUtils.java:85)
at org.springframework.osgi.context.support.AbstractDelegatedExecutionApplicationContext.completeRefresh(AbstractDelegatedExecutionApplicationContext.java:320)
at org.springframework.osgi.extender.internal.dependencies.startup.DependencyWaiterApplicationContextExecutor$CompleteRefreshTask.run(DependencyWaiterApplicationContextExecutor.java:132)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
at java.lang.Thread.run(Thread.java:619)

and many others.

It took some time to figure out that I also needed to comment:

<interceptor name="login-logger" class="com.atlassian.confluence.user.ConfluenceLoginInterceptor"/>

in seraph-config.xml file.