It's been a bit over a month since the release of JBoss AS v4.2.0.GA and we are reaching the 64000 downloads. Considering the large number of changes compared to 4.0.5, I'm quite happy with the uptake and the relative small number of reported problems.
Probably the biggest confusion so far has been the fact that JBossAS binds to localhost by default, instead of binding to all available interfaces. Again, this was done because of concerns of users deploying jboss instances without securing them properly.
Binding to localhost is not a security enhancer, rather a reminder that there are certain steps that need to be taken before going to production. JBoss AS has always focused on developer productivity and ease of use: unzip the .zip distro in a directory and you can start coding.
The switch to JBoss Transactions was another big change. A difference in behaviour of the new default transaction manager is that it will not let you enlist multiple 1-phase participants in the same transaction. This was not the default behavior with the legacy JBoss TM that would log a warning and continue.
There are good reasons for this change, mainly to avoid heuristic outcomes in the case of system crashes, which is the primary reason of using a transaction manager anyway! If your come across this problem you should try to fix it by switching to XA resources or implement some form of compensating transactions. If you cannot do that you can override this default behavior. For more details read the wiki on Multiple1PC, or consult the JBoss Transactions documentation.
Looking ahead, the next release in the 4.2.x series is scheduled for mid-July. JBossAS 4.2.1 will be a bug fixing release and you can peek at the release notes here.
One of the rules we are trying to enforce is for point releases (4.2.1, 4.2.2, etc.) to be only bug fixing releases that don't introduce new features (albeit really minor ones), don't change APIs or introduce any sort of incompatibilities. So upgrading from 4.2.0 to any 4.2.x release should be a breeze (hopefully :)
Thanks for all the feedback, and see you at the forums.
AS Project Lead