http://en.wikipedia.org/wiki/Customs....22mainland.22
http://en.wikipedia.org/wiki/Customs...Hawaii#Driving
Just a little bit of good reading before you arrive in the Islands... With the exception of this one:
Should you cut someone off in Hawaii, you will be looked at as uncourteous [sic], and drivers become very agitated with drivers like this, because it is not customary in Hawaii to cut other drivers off.
I don't know what era the writer of this particular tidbit is from but drivers certainly do cut each other off in this day and age. Doesn't mean you should do it anywhere, though.
But for the most part, the other customs and etiquettes stand true.