Sharing a file and polling it is simple in the sense that it uses file operations, which are something most Java programmers know about. However, there are subtleties to achieving reliable operation. Also, polling a file is quite a heavyweight operation, so you'd either have to accept using quite a lot of the machine's power for this, or polling infrequently and getting slow response.
If the job status information is all you will ever transfer, and it is simple, then the suggestion of using plain sockets is a good one. Sockets use very little of the machine's resources when inactive, but they also respond very quickly to data, when it arrives.
If the job status information is complicated, or you may later extend the application to exchange more types of information, it may be worth using something more capable, from the start. You could consider Web Services, CORBA, RMI etc.
Betty Rubble? Well, I would go with Betty... but I'd be thinking of Wilma.