I think too much emphasis is placed on using servlet filters to 
implement this pattern. When you use includes etc, you will have 
multiple sessions on a single request, basically rendering this 
pattern **useless**. You would expect a filter to surround an entire 
request but it doesn't and as far as I can see this can't be 
implemented this way in a reliable way.

In Struts the only right way to implement this pattern is by extending 
the requestprocessor and closing the hibernate session after the 
action has been processed (process method in the request processor). 
For other frameworks it will be much the same. 

Marc