[plt-scheme] foreign.ss changes? Or, just missing something...

My toy sample:

(require (lib "foreign.ss"))

(define foo
   (get-ffi-obj
    "plus" "native"
    (_fun _int _int -> _int)))

(foo 3 5)

which worked in 299.20-cvs29oct2004, does not in  299.22-cvs23nov2004. 
When I 'Run' the code:

Welcome to DrScheme, version 299.22-cvs23nov2004.
Language: Textual (MzScheme, includes R5RS).
. reference to undefined identifier: get-ffi-obj

In the module 'foreign.ss', I'm confused about the

(provide* (unsafe get-ffi-obj))

which is just one level of syntax too deep for me to unravel. I've seen 
(Eli's?) comment about 'unsafe!' bindings, but I don't quite see what is 
(or is not) being exported.

Thanks,
M