I like the idea of Wifi/internet connected games. Let's imagine for a moment you are an operator, or maybe just a big collector. How nice would it be to get an email notification that there might be a technical alert on your game letting you know a switch is busted, or the game has suddenly started doing ball searches more frequently and you should take a look to see what's causing it, or maybe a game has been getting more than usual tilt warnings or slam tilts, etc... this is all super useful information for me to have access to if I cannot be supervising my games at all times. I still think the JJP games that have a camera should take a picture of someone when they violently tilt out a game, and that could be available in a report on the machine, or if it had Wifi... send me an alert with a picture of the offender!
Usage stats for how many times certain coils have fired, which switches have been hit, game durations/plays or earnings would all be very nice to have access to through some sort of cloud-based interface. If the industry could work together on creating some sort of reporting standard that could dump data into this service, so you could see all of your new games across many pinball companies take advantage of this.
You could opt-in to share your gameplay data with the manufacturer, and they could use this information to make code changes to fine-tune the gaming experience. Think about early on in a game's code which there might be some bugs that cause a crash or some other undesired effect, or perhaps a score imbalance.. this can all be captured and used to help make things better!
Notifications that a new code update is available, and the option to install it automatically, or prompt you to initiate the installation would be awesome. Maybe attract mode could cycle news for upcoming pinball tournaments in your area. On-location machines could publish their high score charts to a Twitter or RSS feed if the operator set it up. Maybe I as a player could subscribe to that feed and see immediately when someone has knocked one of my high scores off a game at my favorite pub!
What about achievements for games? If I achieve a high score or complete some modes, etc... let me put my initials in, and associate those initials with trophies that are awarded for completing each thing in the game. Maybe I can look up a report online for what each player who has entered their initials on a particular machine have achieved.
There are so many things they could do with internet connectivity on these machines I haven't mentioned above! I would love to work on a team that was responsible for building those features into the games!