WebTV Networks Inc. and On Command Corp. said they have formed a venture to offer Internet and e-mail service to hotel rooms. Terms weren't disclosed. Palo Alto-based WebTV delivers Internet content to TV screens; San Jose-based On Command provides TV entertainment in hotels. A three-month trial of the service, whose content will differ from the home version, will start in the San Francisco area this month. In addition to e-mail, users will be able to get information on local restaurants, transportation and maps. After the trial, the companies will settle on an agreement to extend Internet delivery to On Command's access to 1 million hotel rooms. The companies said they couldn't estimate the cost of the service to hotel guests until the trial is complete.