Hi,
On SBCL, providing :timeout NIL to wait-for-input returns immediately even when there is no input on any of the provided sockets (the documentation says it should wait indefinitely).
Attached is a patch (svn diff) which fixes this, but I am not very sure about how sb-unix:unix-fast-select works, so its be best if someone who knows better can review it before committing this patch. :)
Cheers, Chaitanya