Redshift, Druid and Presto are in planning, but in general, we're going to build drivers in the order of community demand. If you have a specific db, open an issue or chime in on one of the open driver issues letting us know it's important.
Support for some of the more common JDBC drivers would be nice, like SQLite, MS SQL and (shudder) Oracle. I know Korma supports all of these (http://www.sqlkorma.com/docs#db), and it seems like you use that.