Twitter's reportedly in talks to buy Tweetdeck for around $50 million. The move would aid power users even as the company looks for ways to boost usage of its newer users -- to get them to keep tweeting rather than lose interest and drop away. The Wall Street Journal says the company "wants to make it easier for new users to navigate the service and help longtime users find interesting content." SFGate says Twitter wants more control over access to its service. It cites a report by Sysomos that says only 58 percent of its users access through "official Twitter apps." Twitter's worth billions but a lot of people still don't know what it's really all about. It has more than 200 million users, but no one -- except Twitter itself, and it's not talking -- knows how many of them are active. A lot of people think it's all about advertising and celebrities attracting attention to themselves -- or trying to.