The old site got taken down by spammers a few months ago (not hackers). I'll rebuild it here in some form or fashion. Meanwhile, enjoy the information site CalendarX at Sourceforge which has all the pertinent information, docs and downloads.
Latest CalendarX source code is in the Plone Collective, in a SVN repository. The /plone-3-compatibility branch is the fun one... works with Plone 3!
If you want to see live examples of CalendarX, just go to google and put this in: "Powered by CalendarX" ( Or click here ) and you'll find several hundred (or more) live sites. There have been roughly 9000 downloads of the most recent version of CalendarX since its release.
Actually, I'll save you some time. Here is one of the prettiest CalendarX customizations I've seen: Diocèse de Quimper et Léon. I just love the oversized event icons. I'm surprised it isn't set up to use the French translation (it's built in!) but nevertheless, it's great.
If you have a problem with CalendarX, google your error message along with "calendarx" and more likely than not you'll find someone else had the problem too. Try that solution first. Then try the calendarx-users listserv that is archived at sourceforge and gmane and search those answers. Then try signing up for the listserv and asking the users. There have been so few bugs that mostly I just say reinstall and try it on a fresh site, dump all your old configuration files (property sheets) and try from scratch... usually that does it.
If all else fails, email the author (me): lupa (at) calendarx (dot) org. Or if you want to send a donation, there's a button at Sourceforge that will let you do that (not many have, but I sure have appreciated the donations I got). Or just send an email of thanks if you like it, that's nice too. Or send offers of a few hours of customization work for me, that I can do from home here remotely on your Plone site. I'm pretty good at getting it to look good and match the colors of your site, and add custom event icons and such :-)
Cheers!