Long Zheng points to function reference in Windows Phone 7 DLL reference, Microsoft.Phone.InteropServices , which was found by Australian developer Chris Walshie which can be used to run unmanaged code on a retail Windows Phone 7 device.
If you find this little Geeky then it simply means that with a Jailbroken Windows Phone 7 you can run any application which is not approved by Microsoft App Store and without any limitation provided by other aspects like Silverlight etc.
Now the question for you, Would you like to Jailbreak your Windows Phone 7 like you might have done for your iPhone. I being a user of iPad now understand why people used to jailbreak their iPhone, too much of restriction. However with Windows Phone 7 there might be less restriction but ability to run apps without much of restriction from any aspect is always exciting to see to how far you can go.