According to an email that Winrumors has intercepted, At&t has completed the testing phase of the NoDo update and is scheduling the update for mid-April.
I know you’re saying, “this can’t be true”, but it seems to be and is only confirmed by the updated Where’s My Phone Update schedule (see below). You’ll notice the highlighted sections which have now been changed to scheduling. This means that delivery is within 10 days for both the Focus and the Quantum (Sorry HTC Surround). For the unlucky Surround users, it appears that you will need to be a little more patient, because the email suggests that the update will not be pushed for your device until mid-May
Hopefully, we can get the last of these updates rolled out to users and start fresh with either an interim update for Windows Phone or an on-schedule Mango update slated for later this phone. Joe Belfiore did mention in his keynote that they have learned from this experience and promise to do better in the future with regards to Windows Phone updates.