In an interview with The Mac Night Owl, an EarthLink spokesperson confirmed reports that they will charge extra for either shared access or simultaneous access. EarthLink, which recently merged with one of its major competitors, MindSpring, was chosen as Apple's default ISP in January.
Same thing applies for Internet service.
The issue arose after The Mac Night Owl received e-mail from an EarthLink member complaining about the practice. When I investigated, I found some additional user complaints were posted at Apple's technical support Web site. The messages have since been removed, more than likely because they don't involve technical questions or issues with Apple's own products. I've asked Rahn how they can determine when more than one person is accessing EarthLink via a single login, and he promises he'll have a response shortly. Only one user can log onto a single account at any one time and there's no way to share the account by AirPort or any other means.