TV networks, always on the prowl for new marketing ploys, are tapping into Twitter. Using the popular 140-word-or-less free instant messaging service, fans can receive (very) short updates and promotions from their favorite shows by text message or email. The twitter-sphere is still relatively small—there were only 370,000 users in June—but marketing execs say they're investing in early adapters.
Fans of Chuck, a new NBC show about a computer geek who becomes a spy, for instance, can sign up for twitters from the title character. But marketing gurus warn of a thin line between informing and irritating Twitterers, who are used to getting messages from friends and not fictional characters—let alone corporations. (Read more Twitter stories.)