Beginning today, we’re giving you more control over what information you share with third-party applications. Apps that you use to access your direct messages will ask for your permission again. By the end of the month, applications that do not need access to your direct messages will no longer have it, and you can continue to use these apps as usual. (Official Twitter Blog)
Since there are many third party apps or websites that merely access Twitter to broadcast a message (i.e. Feedburner, Tumblr, mobile apps, etc.), restricting access should help ease fears that a random developer might be able to peak at messages not meant for public.
It may also help cut down on hijacked twitter accounts due to celebrities clicking on suspicious links (and direct messaging all of their followers with spam).
Hopefully Twitter refines these settings even further to include items like Tweet lists, access to timelines, bio info and the ability to alter ones profile picture.
For those of you who are tweet-a-holics, what other features do you want Twitter to restrict?