I understand your article and benefits you seem to have received through GAE. But apart from sticking it through, I don't see useful message. I would like to know exact scalability issues you faced and how you leveraged GAE infrastructure to tackle them.
We face the same scalability issues as most other startups: a fairly steady stream of normal traffic and the occasional big spike from big mentions on blogs/TV/etc.
We could have done it the same way that we did with DotSpots: EC2 + MongoDB/MySQL. Instead we chose AppEngine to host our system and have spent very little time managing infrastructure.
An added bonus: we've also spent somewhere around $2.00 total to keep the lights on.
