>At the platform level there is an element of implicit lock in because nobody else offers this exact service.

That's kinda what I meant (although there seem to be some similar variants with totally different APIs).

Anything similar will use a different API, as well. Even if you could move to an almost-identical service, there will be not-insignificant switching costs as you reconfigure everything with a different API and reimplement the glue code.

>So IMHO there is no lock in in the traditional sense

Lock-in doesn't mean that it's impossible to move to a different platform, it just means that there's a high cost. To me, it seems like the cost of moving this to some other platform is quite a bit higher than the cost of moving something from, say, EC2.

Actually, it seems like this is Amazon's real business strategy with things like this. They want you to use all of their different services like this, SQS, SES, Elastic beanstalk, their hosted database thing. Individually the costs of moving away from all of them is not that high, but add them all together and it becomes immense.