Apparently the way Google Maps draws one particular section of the border between the two countries is off by about 3000 meters, showing it to be Nicaraguan territory when in fact it's Costa Rican. But looking at the online map and seeing a Costa Rican flag flying there got one Nicaraguan military leader sufficiently rattled to march in with troops and take over, pulling down the Costa Rican flag and raising a Nicaraguan one.
Then they cleaned up a river and dumped the waste over in Costa Rica to get it out of Nicaragua (even though they were, unbeknownst to themselves, in Costa Rica all the while). No shots were fired in the dispute, in part because Costa Rica has no full time military.
This was reported in Costa Rica's paper La Nacion. The paper also suggests Bing Maps accurately reflects the border as it should be. Earlier this summer, Google announced it had revised it's depiction of borders for "over 60 countries and regions."
In Costa Rica, people are mad. So mad, the President appeared on national TV to comfort the public.