Install Mango Beta Update on your Windows Phone Retail Device
Just found this forum thread in XDA developers where files necessary to update your Windows Phone to Windows Phone Mango Beta have been uploaded .
There is also a pdf file that provides instruction on how to install .
To be frank , i am staying away from it . but let me wait for few days to see the result and then decide , but for all those who want to take risk or be adventerous its left to you