It is a separate app from their GC.com version, since that one costs $9.99 and the OpenCaching Network app is FREE.
From their "press release" e-mail...
Geocaching Buddy Downloads Caches From OpenCaching.us
The Netherlands, Rosmalen (October 25, 2011) An update of the geocaching app GCBuddy now allows search and download of caches listed on opencaching.pl, opencaching.org.uk and opencaching.us. Using the OKAPI interface to these sites paperless caching is now enabled for opencaching as a supplement to the already existing Geocaching.com Live interface.
Geocaching Buddy is particularly useful when solving multi-caches. From the cache description new waypoint latitudes and longitudes can be derived from formula's. These formula's contain variables A...Z which are the answers to previously discovered clues. A Multicache is typically prepared at home before heading out. Once in the field, entering the discovered answers will automatically reveal the next waypoint. This dramatically decreases the chance of calculation errors so you can focus on the hiking itself. Just follow the arrow to the next waypoint and finally to the cache.
Traditional caches, puzzle caches and others can also be downloaded in Geocaching buddy. Instead of walking all stages these caches will bring you directly to the cache location.
For the opencaching community a free version called "GCBuddy 4 OC" is now made available. It can be used if you don't want to spend the money ($9.99) for the 'regular' version. This OC version has exactly the same functionality as Geocaching Buddy with the exception of the Geocaching.com LIVE interface.
The author (Wim Verhoef) is an active geocacher with almost 500 caches on his name. More than half of these caches are multi-caches since, according to Wim, "these are much more fun". His team name on GC.com is Team BtSt (Been there, Seen that...).
Wim Verhoef, iOS developer
Promotional video link
Watch the 3 minute overview movie illustrating most of the feature set.
Note that this movie is for V5.X and especially adding a cache is much easier now.
Online quickstart guide
App Store links
Geocaching Buddy: http://itunes.apple.com/us/app/geocachi ... 74229?mt=8
Geocaching Buddy 4 OC: http://itunes.apple.com/us/app/geocachi ... 74099?mt=8
I wonder if Grounspeak requires anyone using their API for an official app to charge at least the same $9.99 they do for the official GC.com app?