Love the idea behind ZeroDB - kudos to you guys, and cheers from a fellow Tar Heel!

What's your expansion strategy for Oracle/DB2/MySQL?

We have ideas how to make relational databases secure while running everything server-side, thanks to recent research publications [notably CipherBase from Microsoft Research http://www.cidrdb.org/cidr2013/Papers/CIDR13_Paper33.pdf] and advances in CPU hardware. Early days, but we'll probably test it first in the open source ZeroDB database [https://opensource.zerodb.com] and then apply the same method to existing relational databases.

If the consuming application (and thus, keys) exist in the cloud as well, does ZeroDB offer any additional benefit over other encrypted at rest dbs?

random ex: https://docs.mongodb.com/manual/core/security-encryption-at-...

I think, you may have the application with a different cloud provider or even in a different geographic location, so that you can keep keys away from the data. In this case you sort of distribute trust.