Baidu is using it for a new application where previously they would have used sharded MySQL (https://www.cockroachlabs.com/customers/baidu/). Their dev team is fairly active on GitHub and Gitter if you want to ping them for more details.
Heroic Labs is using it for real-time, multi-player gaming development that can support a global userbase (https://www.cockroachlabs.com/customers/heroic-labs/). I'm not sure how gitter/github/HN active they are, but they work in open source, so they're probably pretty easy to connect with.
More in the FAQ: https://www.cockroachlabs.com/docs/stable/frequently-asked-q...
We want something with high uptime and resiliency that's going to be relatively easy for us to learn and deploy. We've used PostgreSQL and MySQL/MariaDB more in the past, but those were for smaller applications that didn't have significant uptime requirements.
We could figure things out with PostgreSQL and decide on a fault-tolerant setup, deal with sharding, etc. But it seems like CockroachDB will be an easier path forward, and also make scaling much simpler.
Cockroach was rather pleasant to work with, even in single-node setups, sans not being compatible with ORMs.