I love the idea of waterproof, I wanna take mine swimming! (Just kidding, but I did take my dev kit on a boat and it survived :P)
My biggest wish is for the thing to be flexible and credit card sized! The business card idea is just way too classy to not be a thing. Although, if nothing ever changed and the price DID get down to $10 per unit one day, that would be pretty awesome in another way!
Personally, I like the B&W screen. Limitations inspire creativity; it's fun to put new challenges on yourself as a programmer, game developer, artist, or whatever your passion is! I was drawn to the project because of the limitations-- it will be exciting to see how people will make games work with just six buttons, a beepy speaker, and a tiny black and white screen. The NES, Atari 2600, Vectrex and others all had novel limitations. The games that worked with those limitations, using them to their advantage, ended up being the most memorable and greatest games on those systems! On the Arduboy, I can see the games becoming very bite-sized and gameplay oriented!
Regarding the wireless, I'm not sure whether bluetooth is the best choice. Maybe something like xbee? I'd like to see something that would be able to work in a manner similar to Nintendo DS pictochat. In pictochat, you can join any of 4 rooms. If people are within range and in the same room, they will see your message. Once you go out of range, on their screen you disappear again. I'm not sure exactly how bluetooth works; I've had lots of problems with compatibility among smart phones, with iOS restricting a lot of things, and getting pairing to work.