Microsoft have started rolloing out the Windows Phone 7.5 "Mango" update dubbed as the "Mango Friends and Family Bundle: Pre-Cleanup," actually doesn't contain the Mango bits.
That full update varies from handset-to-handset as each manufacturer has provided Microsoft with a firmware update to be shipped in conjunction Microsoft's Windows Phone 7.5 (aka "Mango") update.
According to Windows Phone NZ, the update is the first in a series of two updates that clean up any devices that have had the beta bits loaded onto them. According to the description on the update (which is available in Zune) it will "clean up any Beta update provisioning on your phone so it can begin receiving updates from production Microsoft servers."
This ""Mango Friends and Family Bundle" update bodes well for the many who have installed an early version of Mango as it suggests most of this group will not need to roll their phones back to the previous release (NoDo) as was first thought. Interestingly it seems this update is coming out slowly as most beta testers were not seeing this when we were. It should be noted however that the previous updates tended to be staggered rather than being available on all handsets at once," said Windows Phone NZ.
This could mean that those on the early beta builds -- such as the pre-RTM 7712 build -- may not need to roll back to NoDo to go to Mango. That's fantastic news for anyone (like us!) that lost their backups.
Microsoft has announced internally that developers will not have to roll back.