A number of users, including some on the xda forums are reporting that they have received notification and have updated their At&t Windows Phones. Some have even reported that they received the update even after using the ChevronWP7.updater tool by Chris Walsh.
This is good news for Samsung Focus and LG Quantum users, however, HTC Surround users will need to be a little more patient as their update is slated for later in May.
Already using the NoDo update myself, I can say that the update, while it doesn’t add a bunch of new features, is greatly welcome. The fixes to the Marketplace are enough to warrant the update and the phone overall seems snappier than before.