This article comes from gigaom.com and contains an bit of an interesting take on the Amazon DynamoDB announcement.
The interesting thing they take note with is that of the service being build upon SSDs instead of plain old HDDs. This is likely the wave of the future as memory/flash prices continue to fall a great rate. HDDs still remain vastly cheaper on a per GB basis and are likely to remain so for the foreseeable future.
Services with SSDs will remain a premium service, but may well be a worthwhile tradeoff for a number of companies. If you can't get enough I/Os on say EC2, then you're pretty much forced to run everything out of ram which can be even more expensive.
It is very nice to see Amazon running services on SSDs and here's hoping the keep going in that direction, especially for EC2 and EBS instances!