You download a free application to your mobile and use it for play to a game, access to weather channel, see stock price or whatever you use it.
This is an interesting article that talks about the abusive situation that exist around the lack of protection of the data stored in your mobile phone.
I see this as an opportunity for those who know how to do it: to create a mobile application that tells you which data is retrieved by each one of the applications that you have installed on your phone!
Fortunately other guys though about it before me: “LBE Security Master”, This app allow you to control each permission of the installed applications (Autorize, Ask me, Refuse), it is implemented for Android.
Unfortunately these apps usually (always?) require root access. This immediately adds it’s own risk, and issues. The alternative can be ADP (Adblock Plus), it will give more functions if you have root, but it doesn’t need root to work.
For the companies, where they are always looking for security measures to protect the intellectual property they should be thinking about this major issue.
Trusted vendors already offer isolated applications that prevent from these issues, with encryption, password access, etc, but nowadays mobile environments are wild wild west.
WordPress
Google + 
Facebook