I definitely have some mixed feeling about the idea of robots roaming around over Twitter. As it is, we already have a significant spam problem there, so I can see the temptation for abuse there.
Despite these concerns, there are also some legitimate uses for tools such as TweetBots. The tool, when used effectively translates into a great to way to automate a variety of Twitter based activities.
Honestly, the ability to auto-follow other twitter users, in addition to posting to multiple accounts does have a certain appeal to it. Sure is a much more effective use of time. Let’s hope that TweetBots is able to maintain a strong anti-spam policy, because with tools this powerful, the temptation is always going to be there.