It was written by Risto Laakso and is hosted at common-lisp.net
NIO is ASDF-installable.
ASDF-install package (obsolete) http://abstractnonsense.com/nio_3.tar.gz
NIO
NIO is a CFFI interface to non-blocking IO. It works at least with OpenMCL / Mac OS X and SBCL / Linux 2.6.