Naval Open Source Intelligence pointed me to a report by the Office of Naval Research (ONR) on the use of multiple unmanned surface assets to protect an asset and if necessary initiate a coordinated attack.
“The technology—called CARACaS (Control Architecture for Robotic Agent Command and Sensing)—is under development by ONR, and can be put into a transportable kit and installed on almost any boat. It allows boats to operate autonomously, without a Sailor physically needing to be at the controls—including operating in sync with other unmanned vessels; choosing their own routes; swarming to interdict enemy vessels; and escorting/protecting naval assets.”
Why should the Coast Guard care? The Coast Guard also protects vital maritime assets including passenger ships, vessels with dangerous cargos, and Navy assets including major ships and ballistic missile submarines so there is that direct application.
The system also appears capable of providing a persistent patrol capability that might be useful in Interdiction Operations. We cannot put a boat crew in a RHIB and send them off to operated as an independent extended sensor for 24 hours, but we could do that with an automated RHIB.
Chuck Hill's CG Blog 
Speaking of remote operation, have you seen this? http://www.spiegel.de/wissenschaft/technik/schiff-ohne-besatzung-hamburger-firma-entwickelt-modell-a-995314.html
I suppose there is an English translation somewhere.
Not a translation, but a story on the vessel in English: http://gcaptain.com/dnv-gl-short-sea-ship-of-the-future-is-unmanned/
Small “short sea” container ship. Not only unmanned, also battery powered. Short range, only 100 nmi. and 6 knots.
A particularly good piece on the demonstration and the implications here: http://www.defenseone.com/technology/2014/10/inside-navys-secret-swarm-robot-experiment/95813/?oref=defenseone_today_nl
Some thoughts on how to use these: http://www.eaglespeak.us/2014/10/us-navy-bring-out-swarmbots.html
A new demonstration.
“While previous work had focused on autonomous protection of high-value ships, this time we were focused on harbor approach defense.”
“During the demo, unmanned boats were given a large area of open water to patrol. As an unknown vessel entered the area, the group of swarmboats collaboratively determined which patrol boat would quickly approach the unknown vessel, classify it as harmless or suspicious, and communicate with other swarmboats to assist in tracking and trailing the unknown vessel while others continued to patrol the area. During this time, the group of swarmboats provided status updates to a human supervisor.”
http://www.navy.mil/submit/display.asp?story_id=98137
Here is another, I think better report of the latest demonstration. http://www.navaldrones.com/CARACAS.html
Thanks to MikeR for bringing this to my attention.