I had to apply this patch to make things work on XEmacs.

First hunk: `calc-trail' does not appear to be used in `ob-calc'

Second hunk: This seems to be a genuine bug (I don't see a '+' syntax
class on GNU Emacs, either), and this is just my guess as to the fix.

-- 
Cheers =8-} Mike
Friede, Völkerverständigung und überhaupt blabla