OK, here's an update on this little script...
The script can now run independently of the UBB.threads server. It will read and post messages using a new server-side script. So it will work whether or not you have direct access to the UBB.threads database from where you are running the Shoutbridge software. It is also possible to run the script without UBB.threads as a Jabber/XMPP bot only.
There is also a plugin system added, with a lot of plugins created. This makes it possible to add functionality quite easily without modifying the script itself.
Among the available plugins is a Twitter integration. This means that all messages can be mirrored out to a twitter account. It can also read mentions to the twitter account and insert these into the shoutbox.
I've been chatting via Adium on the Mac to my site quite frequently in the last months. And I think some of the plugins have increased the usage of web chat as well. One of the commands is an "ice breaker", which can ask questions for the visitors to answer.
More info can be found in the readme on the development site:
http://github.com/ollej/shoutbridge