(This page is about Sanjay Ghemawat's ical, not Apple's iCal or the IETF standard.)
Ical is still (IMHO) the best calendar program for Unix.
I did an RPM for the Fedora Core 2 version since my Redhat 7.3 RPM finally (!) stopped working. Thanks to Richard Jones for the ical maintenance project for maintaining the code; I just did the .spec.
As of Dec. 2004 there are now slightly different versions for Fedora Core 2 and 3.
As of April 2006, a patch is needed to fix a bug in the freeing code. (It's not clear why this bug didn't appear sooner, or what changed to trigger it now.)
As of June 2008, another patch is needed to support tcl/tk-8.5, and there's a new version for Fedora 9.