It's important to note that the Cortana app itself is in beta. I think the most interesting news about Cortana is that, unlike Siri and Google Now, it can be extended by 3rd-party developers.
For example, my Chase Mobile app uses Cortana. By activating her and saying "Chase Mobile ATM", Cortana will launch the app and search for nearby ATMs. I imagine that the GroupMe developers can extend it in the same way: "GroupMe Send 'your message here'".
For example, my Chase Mobile app uses Cortana. By activating her and saying "Chase Mobile ATM", Cortana will launch the app and search for nearby ATMs. I imagine that the GroupMe developers can extend it in the same way: "GroupMe Send 'your message here'".