I just put up a first release of kerberos bindings for ruby on
rubyforge.  The distribution is just a tarball with an extconf.rb, the
c extension, some basic rdocs, and examples in example.rb.  License is
BSD.  This is for MIT kerberos only.  Tested on Freebsd with kerberos
5-1.4.3.  Compiled and minimally tested on linux.  I have no windows
compiler or experience using one, but if someone wants to contribute a
win32 binary I'll be happy to put it up.

http://rubyforge.org/projects/krb5/