The Verge have the official line:
Greg Sullivan, Senior product manager for the Windows Phone division at Microsoft, writes "We are aware of the issue and our engineering teams are examining it now. Once we have more details, we will take appropriate action to help ensure customers are protected."
As they point out the Mango update using the Zune PC software to distribute the update, went incredibly smoothly. Now it's time to see how they cope with a non-trivial bug in the wild. We'll keep you updated on their progress.