"Also, you could do something similar with almost any PDA if you used it to remotely control the PC via something like VNC." Good point, I think there is bluetooth remote control software for the Palms now to control PC's. Or maybe, that needs the internet connection, for now.
Battery life...yeah, limited, but I'm thinking more along the lines of "check the charts, go back to piloting" so it could sleep for 50 minutes or more on every hour. Waterproof? Oh heck, these things fit in ziplock bags if you don't want to buy an EWA pouch of something better.
Me, I just know that every time I go below, there's some kinda problem on deck. Giant Kraken, Narwhal, collision with aliens...Poseidon has made it clear that I'm supposed to Stay On Deck and "do not stand in front of the white line while bus is in motion" so who am I to argue with that?
Best of all, the really really tiny computers KNOW how easily you can chuck 'em overboard, so they are really insecure and they'll do anything to make sure they can crawl back in your pocket. Not smug like the big balky ones that think they run the show.