Sync communication between devices and/or your server is encrypted, but the data is not encrypted on the devices themselves.
If you'd like to see options beyond the existing security tools (FileVault, for example, or remote-wipe of an iPhone), let the
support ninjas know.
The number of requests for a given change is one of the metrics we use to plan our work; thus far, there's been more demand for other stuff. I know we do have some items in the development database along these lines, so they can vote it up on your behalf...