http://www.geocaching.com/ is a geocaching site.
Geocaching-A-Treasure-Hunt-for-Grown-ups.html discusses geocaching.
http://www.funroads.com/rv-travel/gps/ has geocaching information.
http://gypsyjournal.net/geocaching.htm talks about geocaching while RVing.
http://www.geocaching.com/bookmarks/view.aspx?guid=f072e21c-d8fc-46b5-9931-2268f7e8f7d1 has RV friendly geocaches.