There are many satellites doing AIS these days. Some commercial and some operating for governments. It has a huge impact on coast guard activities as you can imagine. All vessels over a certain size is required to transmit an AIS beacon, and traditionally reception was from land-based stations with limited range. Coast guard can now correlate the information in the AIS beacon with satellite imagery and verify them, and can focus on vessels that does not emit the beacon or is falsifying it. It can also be used to find the culprit of oil-slicks.