If you feel like your Windows Phone apps take too long to boot up, you might find a project from MIcrosoft Research's mobile computing research center to be of interest. The group is currently testing context-based application launching, in which the system predicts what apps you're likely to launch, based on cumulative data on the situations in which apps are launched. The system is called FALCON (Fast App Launching with Context), and is part of a broader Microsoft Research project known as "Context Data OS," or ConDOS for short.
Details are minimal so far, but the prototype of FALCON works by analyzing a variety of app usage context, such as "such as user location and temporal access patterns" — the result of that analysis is that apps will "pre-load" content so when the user actually goes to launch the app, most of it will already be loaded into memory. Aside from the rigourous data analysis going into this, the FALCON team is also using a "learning algorithm" to help the system better learn which apps to load and when to load them. There's no word on when this might actually make its way into a shipping Windows Phone, but if the team can get it ready for primetime, it should provide an innovative way to background manage apps.