I've written some scripts to automatically incorporate emailed Exchange calendar events into iCal. There have been other similar scripts, but all the ones I've seen have been intended for Outlook-style plain-text invites, and not the Exchange generated multipart-MIME vCalendar attachments that I receive.
These scripts will correctly deal with UTF-8 encoded accented characters, but currently do not handle event cancellations or modifications.
The scripts are available here.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20031015182931991