I've uploaded this package to snowfort, currently at srfi40/v1.0.1, containing a port of the srfi-40 reference implementation by Philip L. Bewig with adaptations and bug fixes by Andre von Tonder and catfive/chaosnet.org. The code is substantially that provided in the srfi-40 egg of Chicken Scheme.
The package contains some simple regression tests, which are passed by the following Scheme implementations when using the generic snow framework implementation:
bigloo chicken gauche mzscheme
I have also tested with scheme48 (probably a fairly old one, it's the stock Ubuntu package) and scsh 0.6.7. Both of the latter fail the test with the following error message:
Error: undefined variable gensym (package (for-syntax 1 user))
The basic functions such as stream-cons, stream, stream-null?, stream-car and stream-cdr, are tested, plus stream-filter, but not stream-unfoldn, stream-map and stream-for-each.
I would be most grateful for further bug reports or reports of success on other implementations.