That worked perfectly, thanks Michael.
I'm sure there's an easier way to get urlparse.py directly off the 'net, but this is what I did anyway (on CentOS 5) for future reference:
> wget "http://www.python.org/ftp/python/2.5.2/Python-2.5.2.tar.bz2"
> tar -jxf Python-2.5.2.tar.bz2> cp Python-2.5.2/Lib/urlparse.py /usr/lib/python2.4/site-packages/orbited-0.7.0-py2.4.egg/orbited/
As a side note, since this is the only reason orbited fails to start under Python 2.4, I think the urlparse sections of orbited should be made backwards compatible with 2.4 (eg. maybe check to see if urlparse supports using such things like .hostname, and if not then revert back to using a numeric index). There was a ticket made for this request but it was marked as "wontfix" (not good in my opinion).
CentOS is the flavour of choice when building a server for many Linux administrators, and having to "hack" around official packages to get orbited working is not a good thing (even if this is quite a simple fix).
Having said that, I am super-impressed with orbited. Building real-time web apps is now almost only limited by your imagination. Kudos to the orbited team.