I was quite happy to get the Pi LCD display working by following the blog posts, but was disappointed to find that when I had both the MicroStack GPS module and the Display Board connected, the GPS Board stopped working. By a few elementary tests this was found to be caused by the shim board power connections (and probably data as well) not making positive connection on the side connector (the one to which the GPS was connected).
A number of others have commented on this and the solution seems to be to solder the shim onto a 2x20 pin header. I duly went out and procured same, soldered on the shim and, voila.. working GPS on the side connector. On reflection the shim idea is probably OK if it works for people, but I think it is a solution that relies too much on the vagaries of the mechanical setup of the boards on the Pi. Supplying the shim kit with the aforementioned header would resolve the problem.
Now I can progress with writing some software - however an idea occurred to me that in addition to the display, you could also utilise a LED bar graph that is slaved to the distance from the cache point - a kind of 'getting hot, getting cold' indicator that might be more fun for the junior cachers rather than reading GPS coordinates. I'll think about adding that a bit later and see how well it works.