As expected Microsoft today delivered the final bits of Windows Phone SDK 7.1 aka Release Candidate. You can download them here. If you have previous versions of SDK either beta 1 or beta 2, uninstall it completely before installing this new version. This SDK is mandatory for the Mango app submission process, as this build of SDK contains necessary license to submit to marketplace. Microsoft has also started accepting Mango apps from developers. Before getting too excited by submitting your Mango apps to marketplace, keep in mind that you won’t be able to update your pre-mango app once you submit your Mango app to the marketplace. So fix any critical bugs in your older version of apps before jumping into Mango bandwagon.
Another important note, If you have developed any interesting Mango apps and want to share it with Windows Phone community on WMPoweruser, use the contact page to submit your details or email your XAP’s to pradeeplive at live dot com.