It looks like the folks on the Twitter API team have built their own URL shortener and will soon wrap all URLs to protect against fishing and collect stats:
Additionally, as we mentioned at our Chirp developer conference in April, if you want to share a link through Twitter, there currently isn’t a way to automatically shorten it and we want to fix this. It should be easy for people to share shortened links from the Tweet box on Twitter.com.
To meet both of these goals, we’re taking …