In the weekly update to the Windows Phone 7 update rollout, Microsoft warned against using Chris Walsh's update program, saying that it might somehow jeopardize the ability to install future updates, claiming specifically:
But my strong advice is: wait. If you attempt one of these workarounds, we can’t say for sure what might happen to your phone because we haven’t fully tested these homebrew techniques. You might not be getting the important device-specific software we would typically deliver in the official update. Or your phone might get misconfigured and not receive future updates.
Meanwhile, there is no progress for customers on AT&T in the US, Deutsche Telekom/T-Mobile in Europe, Telefonica in Spain, or Optus and Telstra in Australia. These laggards are still claiming to be "testing" the NoDo update. AT&T is still claiming to have the testing completed in "early April," but with a week already gone, that's looking dubious.
As for the warnings about ChevronWP7.Updater, well, they would say that, wouldn't they. If there's even the slightest possibility that the updater will break something, Microsoft plainly doesn't want to be on the hook for resolving the problem.
However, problems still seem highly unlikely. Though some users have reported issues with the program, these stem from a failure to actually follow the instructions and not any fundamental flaw with the upgrade process it uses. And given that the updater uses unmodified firmware directly from Microsoft, and uses Microsoft's own support program to install that firmware, the opportunity for it to do something wrong is slim.
Chris Walsh has pulled the program from his site. Though he has claimed this is due to hosting issues, some have speculated that Microsoft requested the software's removal. If this is a result of Microsoft pressure, then—just as with the pulling of the original ChevronWP7 device unlocker—it's a futile gesture, as mirrors are already available.