We are very excited to announce that we've finally released the "labels" feature. To try it out just go to the project page then: Project > Labels.
On the surface, it is a replacement for categories that allows you to apply multiple labels to the same story.
But there's a lot more power to it should you chose to use it. You can define custom fields, acceptance tests, and tasks for a label. And when you apply a label to a story, the story inherits all of the attributes defined for the label.
We have more things planned too for this feature, but we also wanted to release it as early as possible to get it in the hands of our users.
It is much easier to use than it is to explain, so be sure to give it a try and let us know what you think.