Symantec Encryption Desktop drive encryption and Symantec Endpoint Encryption are being merged. The initial release is really geared towards new or existing managed environments to begin migrating towards the new underlying management system for whole disk encryption.
Symantec Endpoint Encryption version 11 does not have a direct upgrade path for clients as of yet. The clients would need to be uninstalled, then the new client packages would need to be created and installed. Direct upgrades for existing client systems should be coming in the next major release, which will not be out until next year.
If you would like to switch your standalone installations to SEE version 11, you can find instructions for installing the required components to generate standalone packages here:
http://www.symantec.com/connect/articles/symantec-endpoint-encryption-server-less-installation
Again, you would need to decrypt existing drives, uninstall Symantec Encryption Desktop, then install the new standalone packages you generate through the above process. Let me know if you have any additional questions. Thanks!