I’m currently working with the maintainers of the Debian ejabberd package to add GSSAPI/Kerberos support. As it will be surely be a while before the new packages find their way into the Debian repository, and even longer until they find their way into Ubuntu, I’ve created a PPA containing packages for the current version of ejabberd (2.1.13 at the time of writing) with the GSSAPI/Kerberos patch and the esasl module on which the GSSAPI patch relies.

The PPA can be added to your system manually by copying the lines below and adding them to your system’s software sources.

deb http://ppa.launchpad.net/ngroot/ejabberd-gssapi/ubuntu precise main 
deb-src http://ppa.launchpad.net/ngroot/ejabberd-gssapi/ubuntu precise main 

If you would find packages for another distribtion of Ubuntu to be useful, please comment and I will try to accommodate your request.