Twitter's website begin counting clicks inside of tweets. Obviously, they do this to track stats, i.e. how many people click on links from the Twitter web site.
The interesting thing is that they're passing on the simple referrer that you'd expect. In other words, instead of the referrer looking like:
It simply looks like:
This is very clean for link tracking websites like Adjix which track clicks by IP address and referrer:
Update: Just discovered a clear downside - when the Twitter website is slow, clicking on these links are painfully slow since you have to first be redirected by Twitter's servers.