According to Amazon Web Services they have announced encryption support for EBS volumes. EBS encryption will enable users to meet strict security and encryption compliance requirements and at no additional cost.
You can now create an encrypted EBS volume and attach it to a supported instance type. Data on the volume, disk I/O, and snapshots created from the volume are all encrypted.
The encryption occurs on the servers that host the EC2 instances, providing encryption of data as it moves between EC2 instances and EBS storage.
You can use and manage encrypted EBS volumes and snapshots via the AWS Management Console, Command Line Interfaces (CLIs), Amazon SDKs, or the Amazon EC2 API directly
To create an encrypted EBS Volume Via the AWS Management Console,
1 - Log on to the AWS EC2 Management Console, Under Elastic Block Store, Click Volumes
2 - Click the Create Volumes button, Fill and choose the options as necessary and select the encryption check box (remember to create the volume in the same AZ as the instance yo want to attach it to)
Please Note: you cannot enable encryption for an existing EBS volume. Instead, you must create a new, encrypted volume and copy the data from the old one to the new one using the file manipulation tool of your choice, i.e. Rsync on Linux and Robocopy on Windows.
For More Information: Amazon EBS encryption now available