You probably heard about the Twitter's new interface which has been released on Tuesday night (September 14th). I didn't write anything about it because I didn't have time for almost anything on the last few days. So, this is one of the most important changes Twitter did to its official website until now.
However, there are some users who don't see the change even two days after the change has been released (I also don't have it). The change is rolling out progressively, so there might be a few more days to wait for some users to get it. As it writes on its official blog, the update started rolling out on that night for a very small number of accounts, and it's probably still rolling out for some accounts.
What's changed, as I've told you, is the interface which has been redesigned, maintaining its simplicity. Twitter also got more user friendly. It's now possible to view embedded photos and videos from DailyBooth, deviantART, Flickr, Justin.TV, TwitPic, USTREAM, yfrog, YouTube and others. You can now see related content, meaning you can see replies to a tweet, other tweets by a user, the location from where a tweet has been sent, and more. Moreover, you now have "mini profiles", which allows you to view quick information about someones account, without having to leave the page you're on.
Over the following few weeks, both versions of Twitter will be available. The possibility of changing between interfaces allows you to accommodate easier with the new one. We'll see how the users will reaction when the old one won't be available anymore (because there are people who don't like the progress and the change).