Single user jabber servers feel like overkill - you're going to need to federate with other servers to get any use of it (and this needs to be turned on at the other server), and no current package is designed for a single user as a result. I have set up and run [openfire][1]openfire and its well documented, easy to maintain and really easy to administer. You can get one up in about 10 minutes, though I suppose its not the lightest option rather large, and not lightweight, needing a database for example.
I've also heard good things about [prosody][2]prosody and it looks even more lightweight - it has a text based backend, is modular. Its also in active development. It might be a better option, but I've not tried it myself yet.
In both cases, you may end up preferring to install from source to get the latest version, rather than relying on the repositories. This isn't entirely a bad thing for personal use, though i'd consider it a pain in production. [1]: http://www.igniterealtime.org/ [2]: http://prosody.im/