Eric Hautala is back! With some more good news regarding the Mango roll out, which has now been bumped up to 100%. Everyone is now set to receive the notifications to update their NoDo powered handset (be sure to keep an eye on Where's My Phone Update?), up from 50% only two weeks ago.
The LG Optimus 7 on Telefonica in Spain is now being scheduled, finally. Eric mentions that work is still ongoing, for example with Orange FR where technical difficulties are preventing the network and Windows Phone team from pushing out the update at full speed.
On a side note, you may receive a notification of an update after Mango has been applied, which will be firmware related.
One last thing. Next week we’ll start delivering some model-specific “firmware” from handset makers, so don’t be alarmed if you receive an additional update notification on your phone. These updates are designed to activate new Windows Phone 7.5 features or improve your phone’s performance. Not everybody will receive or require one: It all depends on your country, carrier, and phone model.
We're not yet aware of which handsets will be receiving this firmware, hopefully more information will be made available soon. This could well be the missing WiFi tethering drivers.
Source: Windows Phone Blog