Scala has worked out very well for us. We introduced a similar stack (Scala services backend "data switches" with various front ends using the APIs. For your Java team Scala will be a snap to pick up, and undertaking to master. But the nice thing about is everyone can be fully productive as more and more advanced techniques find their way into code. Scala code can be made overly complex in the wrong hands. So can Ruby and Python :)
A lot's been written about why Mongo, what are problems it is singularly suited to solving. At Bookish, we're using Mongo for a use case clearly not well-suited to a relational structure, where the ability to query by elements other than document key are essential. So far so good.
Newco, stealth mode well-funded NYC startup with lots of runway. Huge opportunity to join a small team building a very busy gamechanging consumer Web app. Hiring several developers. No legacy code- build this from scratch with us! RoR/jQuery front end, Scala for the heavy lifting and API.
A lot's been written about why Mongo, what are problems it is singularly suited to solving. At Bookish, we're using Mongo for a use case clearly not well-suited to a relational structure, where the ability to query by elements other than document key are essential. So far so good.
(Andy Parsons, CTO at Bookish)