What? You mean without a backup plan to substitute in for the platform with known reliably issues? Yeah I guess that would suck.
Edit re your edit on dogfooding: supposedly they use the same tech, just not the same servers, so their AZs are probably separate form ec2s. Also, they're in all of their geographical locations, not just us east.
Wow - looks like you're right! I dug into the presentation (link below, important slide is #33) and Amazon are now claiming that all their web servers run on AWS. It's only their webservers (not their DBs, load-balancers or "services" which I presume means anything stateful). Of course, the co-location option for 'difficult' services is only available to Amazon, and before the switch-over in November they presumably weren't using AWS nearly so heavily, but this is at least a step in the right direction.
Edit re your edit on dogfooding: supposedly they use the same tech, just not the same servers, so their AZs are probably separate form ec2s. Also, they're in all of their geographical locations, not just us east.