The latest and greatest EMACS from CVS breaks CEDET on my Linux box.  Looks like they changed the name the default byte compile output buffer.  The following change worked for me.  This is for edification only.  A proper patch would have to take into account the EMAC's version.
Index: eieio/eieio-comp.el
RCS file: /cvsroot/cedet/cedet/eieio/eieio-comp.el,v
retrieving revision 1.14
diff -u -r1.14 eieio-comp.el
--- eieio/eieio-comp.el    29 Sep 2008 00:18:57 -0000    1.14
+++ eieio/eieio-comp.el    26 Jul 2009 23:11:58 -0000
@@ -78,7 +78,7 @@
      (class (if (listp arg1) (nth 1 arg1) nil))
      (my-outbuffer (if (eval-when-compile
                  (string-match "XEmacs" emacs-version))
-               byte-compile-outbuffer outbuffer))
+               byte-compile-outbuffer bytecomp-outbuffer))
     (let ((name (format "%s::%s" (or class "#<generic>") meth)))
       (if byte-compile-verbose