GNUstepWeb
GNUstepWeb is a development framework for web applications written in Objective-C which is designed to be source-code compatible with WebObjects 4.5 - a product originally developed by NeXT Inc, whose newer versions have been released by Apple and are Java-based.
Availability
This library is a component of the GNUstep project in the dev-libs section and is available in the standard ways - such as the GNUstep ftp site.
David Wetzel recommends using his recent branch that can be obtained by executing the following SVN check out in an empty directory
svn co http://svn.gna.org/svn/gnustep/libs/gsweb/branches/06-02-dwetzel
Documentation and Resources
Apple has legacy WebObjects 4.5 documentation available. Please note that the official site is gnustepweb.org is somewhat out of date.
David Wetzel runs a low-volume mailing list called gswhackers.
Tutorials
Creating A Simple GSWeb Application is very easy.