Indigo is a voice controlled personal assistant for your Windows Phone 8 device. The app was recently updated to version 18.104.22.168 which gives the app the ability to launch the app from the Windows Button.
Now according to the change log you should be able to execute some predefined inputs by pressing the Windows Button but the best we could do is simply launch the app itself. Every time I said "Indigo + [your question/request], a Bing search was launched. Granted my Southern accent could be getting in the way but it feels as a little more fine tuning is needed.