http://maps.google.com/maps?q=...hl=en
just type in guthrie as your starting location (or you can zoom out, you will be heading down I-35, exit I-240 West bound and then exit penn.
it is in the parking lot where joes crab shack is, meet starts at 7pm but most people are a little later than that.
unfortunatly i won't be there at this meet, but everyone is pretty friendly so just walk up to someone standing by all the 240s and introduce yourself.