On June 30, 2010 (8 weeks and 6 days from now), the @twitterapi team will be shutting off basic authentication on the Twitter API — you can see the announcement here (and, this has been previously announced). All applications, by this date, need to switch to using OAuth. Don't fret! @twitterapi is here to help! Feel free to reach out to us directly, or via our Twitter Development Talk group.
The switch to OAuth is a good thing! You, as the application developer,
don't have to worry about exposing the credentials for your users whether through a bug or other means (especially considering that a lot of people use the same password for multiple services);
don't have to worry about the user changing their password — a user can change his or her password and the OAuth "connection" to your app will still work;
don't have to worry about other applications masquerading as your application as only your application can set the byline with your application name;
will eventually have access to more APIs from Twitter that will only be available to "trusted" OAuth-enabled applications; and
give the @twitterapi team more visibility into the network — you help us identify your application when there are bugs, you help us plan for capacity, and you help us squash spam.
yc c on 17 Feb 10Twit Cleaner gets your following list, then analyses the profiles & tweets of every single one of those people, looking for certain patterns of behaviour (people not talking, being over repetitive, common spam tactics, posting the same links repeatedly, etc). It's then up to you to decide who to save & who to unfollow.