While development of my NFC Toolkit, I came to the point where I needed to launch apps from my code.
On Windows Phone, this is only possible via custom uri association and needs to be implemented by the developer of an app.
If you want your app to be launchable from other apps, you need to implement a custom uri assocation like descriebed here in the MSDN Documentation.
Users are demanding often apps to be launched from other apps – it is not much work to do, so I recommend you are implementing those features into your app(s). Over time, your app will be getting more recognition amongst users of other apps and improves the user experience a lot.
To make it easier for everyone of us, please add your app here: http://developer.nokia.com/Community/Wiki/URI_Association_Schemes_List
Let’s make this list a basic resocurce for everyone of us!
Until then, happy coding!