If you're not too worried about security, you can always generate a
session similar to the way it's done for a web server (which honestly
is done from the ultra lame to the insanely overly complex).  I didn't
notice a session id method in the standard Net/HTTP library, but that
doesn't mean there isn't one.

If you don't want to come up with your own, this article examines how
RoR generates session IDs*.  It ends up being very simple, easy to
understand code
http://epsilondelta.net/2006/05/17/examining-rubys-http-session-id-generation/

Good luck.
--Kyle

* Or at least how RoR generated session IDs in 2006.