This task does seem to have Erlang written all over it, but of course we're not intimately familiar with all the details.
The mindset for selecting tools to build apps which need to scale seems be similar to the one we all had back in early dos days, when the company programmers were having to write all the internal software. We were either unaware of better solutions or we simply felt compelled to write all the stuff ourselves, from spreadsheets to a GL module. Now, with all the customizable apps around, why would anyone want to write a custom GL module?
By extension, why try to reinvent solutions for scaling problems when Erlang already does a bunch of the work for you?
Erlang makes distribution and concurrent execution semantically identical, Scala doesn't. And there doesn't seem to be a good reason to base on the JVM, they aren't already next deep in Java libraries.
I'd really like to know what they're thinking over there.