John,
I used your jabber howto to install under SME 6.0 final. The instructions still seem to be valid. I didn't have any problems running the install script and getting jabber installed. The howto graphics are missing.
I used the server manager to enable the particular jabber services I wanted, used the jabber user panel to enable my users. I used the exodus client as winjab is being deprecated for exodus.
I didn't try any of the transports.
Here are some things I see:
The jabber and jabberuser server manager panels show up in the unknown section. I tried to look at this, but I don't know enough Perl nor know the format of how items are placed on the server manager screen. If you can shed some light on this, I'd appreciate learning something.

By default, users can (using Exodus - anyway), register any userid and password and gain access to the jabber server. If you go to the server manager panel, the users defined on your system still show up as disabled, but they are actually enabled if they auto-registered. Enabling and disabling the account is one way to then disable that user. But, of course they could just register again via the client. Also, userids that are not defined in your system, but have a registered jabber id, don't show anywhere. These users have to be removed by going to /opt/jabber/spool/
and manually removing those ID's. I tried changing 10jabber-reg to no to see if that would turn off the automatic registration, but that didn't work, so I removed the whole section all together, and that didn't work as well. I did do a service jabber restart after all of my changes. I started reading the jabber docs and will do more research in this area to see if I can find a way to not allow automatic registration.
Also by default it looks like server to server communication is enabled via 5269. I'd like to see this fragment further broken out. One section for the 5222 stuff, and another for the 5269 stuff. Or, you can take the view that someone can further beark up the templates to suit themselves. If you do break them up, then an admin could remove the 5269 fragment. That way it will give an admin the ability to enable this function if they want.
That's just my 2 cents worth. Hope some of this info helps. I'd be glad to test anything that you put together.
Thanks for creating the howto,
JB