Project page: nilsimsa RubyForge project page.
Wiki: nilsimsa wiki
From cmeclax's page:
A nilsimsa code is something like a hash, but unlike hashes, a small change in the message results in a small change in the nilsimsa code. Such a function is called a locality-sensitive hash.
Martin Pirker (mpirker) is responsible for the port, but Jonathan Wilkins (jwilkins) is the new maintainer so bug him with problems.