I've had good luck using IPC::DirQueue for a fifo queue that I run. It doesn't process as many items as you are talking about, but it is supposed to scale pretty well, and is transactional ( like Websphere MQ ). It is also supposed to be quite scalable, using NFS mounts ( I think ) to distribute the queues.

It definitely seems to be worth a look. It works wonders for me, and has been ultra-reliable.