I have been using JBoss 4.2.3 for over a year right now and really like it (although the clustering / JMS stuff seems WAY overcomplicated - and needing 80 config files - not fun!). But anyway it is time to upgrade to JBoss 5 and the path has been marred by many stops and starts and has been surprisingly difficult.
In any event I found the following links to be a life saver and thought I would share them
1) Increased adherence to the Java spec that cause WARs / JARs to no longer deploy
2) Changed location of XML files
3) Changed XML filenames
4) Changed XML file contents
Man they don't make it easy do they?