Twitter has become a huge part of TV networks’ strategy to get the word out on its shows, so it’s no surprise Fox and CBS are turning to the social networking site as part of its fall promo campaign. A survey by Bluefin Labs recently reported in the Wall Street Journal found that comments posted on Twitter and other social-media websites about television shows have exploded in the past year, to 75.5 million in July from 8.8 million a year earlier.

Following that trend, Fox announced today that fans can get a sneak preview of the Season 3 premiere of Raising Hope on the comedy’s Twitter page in advance of its on-air debut October 2  — the first time a full episode of a TV series has been available on the social networking site. It’s available now through next Thursday at 11:59 PM. And CBS follows next week, kicking off its #CBSTweetWeek @ the CBS Connect Lounge. The network says fans will have direct access to their favorite CBS Television Network stars with a week full of social media events September 24-28.

Fox says fans who share the commercial-free premiere with their followers on Twitter may also receive a special thank-you message from the Raising Hope cast. Raising Hope is produced by Amigos de Garcia Productions in association with 20th Century Fox Television. Garcia serves as executive producer.

CBS’ Tweet Week will be hosted in the CBS Connect Lounge on Fans will be able to chat live with CBS stars, producers and creative talent during the East Coast broadcast of their respective program’s premiere. Fans will also be able to follow conversation streams about their favorite CBS shows and participate in social polls around the premiere episodes. Those who wish to participate can go to the CBS Connect Lounge and log in with their Facebook or Twitter accounts to chat live or follow the hashtag #CBSTweetWeek on Twitter.