Don't you hate it when you figure out a bug only to forget it two weeks later? This usually happens with those bugs which aren't your fault. One such bug I came across recently, was when I was using XFire 1.2.6 and Spring 2.0.2.
When trying to view the wsdl for the service I got the following error in the tomcat logs:
SEVERE: Allocate exception for servlet XFire org.springframework.beans.factory.BeanDefinitionStoreException: Unrecognized xbean element mapping: beans in namespace http://xfire.codehaus.org/config/1.0
It turned out that I had solved this on another project just two weeks ago but I forgot about it completely. I only remembered when I found the solution again.
Basically XFire needs an earlier version of spring to work. I ended up using spring 1.2.8 but I assume any spring version before 2.0 would work. I hope this helps someone else and prevents a few wasted hours.