Now it's all over the net:
Make magazine: http://blog.makezine.com/archive/2011/01/nixie_tube_reverse_geocache_box.html
Gizmodo: This Clever DIY Briefcase Only Opens When You're at the Right GPS Coordinates
and various other sites. It's kind of cool, but I really hope the guy who this box is for (his birthday is in 4 days) doesn't stumble over it :-/