In the previous recipes, we saw that the model of the WP7 OS is such that only one application can be running at any given moment (apart from a few built-in applications). The big advantage of this model is the performance benefit. No longer can an application that's running in the background leak memory and in the end, lock up the entire device. With the single running application model, all these are memories of the past. Of course, it's not all good. On some occasions, we may want to receive updates from an application, say a stock application. To receive these updates, the application must be running. On the other hand, we want to use the phone for other applications in the meantime as well. This seems, at first hand, an impossible thing to do.