A couple of months ago I saw that Sky & Tel were organising a cruise from LA to Hawaii and back beginning on August 1. Unfortunately, we couldn't make it due to work etc. Anyway, I just checked the Sky & Tel website and unfortunately they had to cancel the "astronomy symposium" content from the cruise..
However, the cruise is still on. If you want to see where they are (or where I would have been) follow this link and click on the "bridge cam".
http://www.princess.com/ships/gp/index.html
Currently they are on the way to Hilo where one of the optional tours is to go to Mauna Kea summit