For all the redundancy in their networks and architecture, this has obviously exposed a single point of failure somewhere in the process.

I have sympathy for them though. These kind of cascading failures are difficult to predict and Google are victims of their own success to an extent. Google apps is a great product and if Microsoft had anything like this, we would be used to having these kind of outages every few days rather than every few months (any big corporates switched to hotmail? no - I thought not)