I've just been shown a nifty little trick that upgrades your Windows 7 phone to the latest update - even when it hasnt been released yet.
Microsoft have a strict release schedule and are sticking to it, however the updates that they have lined up for the next few months are all sitting on their servers waiting to be downloaded.
Just plug your phone into your PC, once Zune loads up, click on the phone icon in the bottom left, then click on 'Settings' on the Top right of the window.
Select 'update' and let it register what updates are currently on the server. It should say that you are up-to-date and have none to download.
Now leave this screen (click OK).
You now want to go back to this update screen, but as soon as you do, unplug your network/internet connection. It will sit there saying "checking of updates" for a few seconds and then, becuase its not being told to 'censor' the unreleased updates, it tells you you have updates to install
plug the network cable/internet back in and select 'OK'.
E voila, you now have Mango downloading to your phone as well as other updates which havent been released yet.