With the official launch they enabled a couple of features that had been discussed in the past: commit comments (I still don't know if I like them or not), and integration with Campfire and Lighthouse (although you can also roll-your-own integration using their hooks).
One feature though, was not on the roadmap, and its a beauty: an network graph visualizer.
Its a great view across several repos, and it works very well. As far as I know there is no tool on the desktop that gives the same view. Not even