after testing the "upgrade" to the long awaited version 5.2.2 (I can describe the procedure as well if you are interested) I got some nasty problems with hibernate.
For the portlet "EasyComments" hibernate3 worked fine so far - but suddenly I got the following errors:
Could not initialize class HibernateUtilAnnoyingly there was not more to take from the standard out of tomcat (nor from the logs). Only an additional catch blog in the HibernateUtil class showed the real problem:
org.slf4j.LoggerFactory not found
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder"
So it seems that hibernate is using slf4j internally.
Adding the following jars solved the problem:
The files can be found here:
And finally all worked again.