Google confirmed that the performance issues the past few days were
related to configuration changes they made during this past Monday's
scheduled maintenance. They believe they have fixed all the known
issues, but will continue to closely monitor performance to detect
signs of any regression.
Again, I do apologize for the trouble this has caused you in managing
your work. Unexpected errors and downtime are an unfortunate reality
of any web service. However, with GQueues built on Google App Engine
we have some of the best engineers out there to solve problems when
they arise.
-Cameron