in Australia, definitely a Poker Machine, but we rarely use the word 'Poker' to describe someone who uses (or abuses) a Pokie. nor do we say 'go for a poke' which sounds more like a sexual connotation over here ;) most often used in the plural, Pokies.
A Poker Machine. They eats your money, giving an average return of 75-85 cents per dollar outlayed.
The bright lights, soundz and gambling is all extremely addictive and one can become a 'pokie junky', 'pokie fiend' or 'poker'.
Gambling Addict: "Let's go for a 'poke'."
Concerned Friend: "Man, your a 'pokie fiend'."
Gambling Addict: "Yeah, I am a hardcore 'poker'."