That patent was filed back on March 25, 1987 by some folks at Xerox/PARC, which means that prior art dated before that date is helpful -- and art dated before March 25, 1986 is the most useful. (That means art found in a Linux distribution may not help, seeing as how Linus Torvalds first began the Linux kernel in 1991.)
Red Hat has invited the community to join in the fight against the patent trolls by identifying prior art. They are coordinating efforts through the Post Issue Peer to Patent site, which is administered by the Center for Patent Innovations at the New York Law School, in conjunction with the US Patent and Trademark Office.
A noble goal, if you ask me. Patents should be a tool to foster competition - not one to just make money and consequently stifle innovation. I strongly believe that any filed patent should be accompanied by a working prototype (instead of just some vague drawing a la "warp drive goes here"), and that only that specific implementation as used by the prototype is covered by the patent. If that patent is not used in a product within, say, three years, the patent becomes void, allowing others to do a better job of doing so.