I know it's not really the same as letterboxing, but it's not ALL
that different. I found the following article at CNN.com:

http://www.cnn.com/2001/TECH/computing/02/01/geocaching/index.html

My wife and I planted two letterboxes in Prince Edward Island and
Nova Scotia last fall, but haven't written the clues up yet.
Fortunately, we wrote down compass bearings and other notes so that
we can write the clues. Is anybody going up that way in the next few
months? If so, we'll get going on the clues ASAP and post them to
the letterboxing web site, and here as well.

I hadn't been following the discussions here much, so I didn't know
about the CT gathering until two days before (and I live in East
Haddam, CT). So I'm sorry I missed everything.

Chris