I don't know, S3 and DynamoDB are both eventual consistent. And keeping in mind the CAP-theorem it makes sense. And I for one love SimpleDB - it's just that, simple. And great for prototyping (really cheap) and small production-loads. Often you just need a place to stick your data, scalability can be achieved to adding a caching layer.
You can choose eventual or fully consistent in DynamoDB. Given that full consistency comes at a higher cost (read from a quorum of replicas) we expose that cost to you.
BTW nobody wants eventual consistency, it is a fact of live among many trade-offs. I would rather not expose it but it comes with other advantages ...
They have actually been making S3 _more_ consistent over time: in the newer regions you get e.g. read-your-writes for object creation. DynamoDB also supports consistency, though still defaults to eventual consistency if you prefer.
In my mind, there's definitely a trend towards consistency here. I'd love to see an AWS blog post about the reasons behind this!
