(late reply)

it's pretty hard to google akka deployments but:

http://www.quora.com/What-companies-are-using-Akka-commercia...

http://groups.google.com/group/akka-user/browse_thread/threa...

and in terms of memory overheads and how many erlang process-type things you can spin up:

http://akka.io/docs/akka/1.1/scala/tutorial-chat-server.html