SessionMonitor.java contains a char encoded perhaps in ISO-8859-1 yet build.xml's <javac> specified no encoding. Produces a compiler warning when running in UTF-8 locale, the default for new Linux distros. Better to be safe and use ASCII:

Index: src/com/ecyrd/jspwiki/auth/SessionMonitor.java
===================================================================
RCS file: /p/cvs/JSPWiki/src/com/ecyrd/jspwiki/auth/SessionMonitor.java,v
retrieving revision 1.1
diff -u -r1.1 SessionMonitor.java
--- src/com/ecyrd/jspwiki/auth/SessionMonitor.java	25 Jul 2006 03:45:27 -0000	1.1
+++ src/com/ecyrd/jspwiki/auth/SessionMonitor.java	18 Sep 2006 17:01:33 -0000
@@ -26,7 +26,7 @@
  *  Only one instance exists per WikiEngine. It is a not a 
  *  daemon thread; rather, it listens for wiki engine shutdown 
  *  and persists in the JVM until it detects it.</p>
- *  <p>The <em>raison d'être</em> for this class is to work
+ *  <p>The <em>raison d'etre</em> for this class is to work
  *  around the fact that we need to keep track of HttpSessions
  *  and know which ones have expired, and which haven't. We can't
  *  t query the web container directly to see which have expired. As

--HarryMetske