I think that you're thinking of OCSPD. OpenCA has a project going for the development of an HTTP-based OCSP responder. There's also an OCSP going under OpenSSL. See:

http://www.openca.org

There's a module on CPAN= Lemonldap::Portal::Sslsso.

mod_ssl has ocsp functionality now.

Before you use the Lemonldap module, get the Lemonldap bundle and web-admin packages from Sourceforge. See:

http://sourceforge.net/project/showfiles.php?group_id=89702