It's just a library for rpc, so yep, just memory. I'm planning on writing a rails plugin to save blocks/transactions/operations to a database. You'll be able to use any dbms rails supports. The default will be sqlite3.
The nice thing about the plugin is that you can just use it to save the blockchain and use it independent from the plugin. Or, if you want, you can use the plugin to embed in an existing rails app, all in its own namespace.
Don't know if you golang at all, but:
github.com/faddat/steemjson
is the golang expression of such ideas.