local xml files in c#

http://dotnetslackers.com/articles/silverlight/Windows-Phone-7-Silverlight-Programming-Handling-XML-Data.aspx

lock screen em seus apps do windows phone

http://msdn.microsoft.com/en-us/library/windowsphone/develop/jj206968(v=vs.105).aspx

Audio em Background no Windows Phone

http://msdn.microsoft.com/en-us/library/windowsphone/develop/hh202978(v=vs.105).aspx