Amazon is working on a significant new feature for the EC2 service: persistent storage. According to this pre-announcement post in the developer forums, EC2 users will be able to create storage volumes that exist separately from individual instances, but which can be attached to your instances on demand. These storage volumes will look like normal block devices to your instance, meaning you can format and combine them in any way you want.
The persistent storage feature is still in the testing stages and is not yet available to the general public. There is more information available on the Amazon Web Services Blog and on the RightScale blog, where they have access to the trial version.
A robust, flexible and reliable persistent storage mechanism could revolutionise the EC2 service, and will definitely simplify the process of deploying your applications to the cloud. However, I wonder whether this feature will damage the third-party providers who already offer persistence solutions for EC2.
As Amazon continues to develop and improve their infrastructure services, they will need to be careful to avoid wiping out the third-party vendor ecosystem based on these services.