It should compile cleanly under Emacs 21.3 (CVS). I’m still trying to
figure out how to install the fsf-compat package under XEmacs so that
I can get it to compile cleanly there.

WARNING! Many user-visible changes. In particular, you will now need
to require a bunch of other things in order to get the old behavior. I
should figure out how to set up the appropriate autoloads. In the
meantime, add some variant of the following to your .emacs:

(require 'remember)
(require 'planner)
(require 'remember-planner)
(require 'planner-experimental)
(require 'planner-bbdb)
;; (require 'planner-diary)
(require 'planner-gnus)
(require 'planner-id)
;; (require 'planner-notes)
(require 'planner-rss)
;; (require 'planner-schedule)
;; (require 'planner-timeclock)
(require 'planner-w3m)

This will no doubt break a number of things. Please complain loudly.
If you want the old version, you can get a tar.gz from
http://sacha.free.net.ph/notebook/emacs/planner/planner-current.tar.gz
.