I agree... the fun is in the search (and also to some extent there is a certain frustrated sick pleasure in correcting Northernpenguin's math, but that's another story )
There are lots and lots of "myths" regarding GPS, and centimeter accuracies are definitely possible even in the commercial world. One of my Customers (Trimble Nav. in California) gets amazing accuracies with their system, but we are not talking about cheapie handhelds like we all use.
Here is a really fun on-line dump on GPS:
GPS Tutorial
worth the visit.
