Just wondering- it seems like a way to see and be seen other than radar. Looks like the VHF broadcasts your position/speed/heading and you can see other big traffic that requires AIS and little traffic that has optional VHF AIS radios.
Might be a big help at night.
And you can look at AIS vessel locations from the web:
http://www.marinetraffic.com/ais/
Pretty neat stuff... I am looking at a Standard Horizon GX2100 or 2150 for this.