Any ideas for scaling?

I was wondering if you have any idea about putting behind a load-balancer. (Given that we avoid trying to route requests from the same client to the same machine)

What I am wondering about is chunked uploads would only work if the temporary place where the chunks (chunk since one of our previous discussion) is stored in a shared place.
But then again, it would mean the latest-chunk is uploaded to the server, the remote file read, the latest-chunk written to it, and saved to the shared place again so the next request can access it from a possibly different server and then moved to it's final place. Sounds pretty un-effective to me.

Do you have any ideas how we could improve this, or if my I miss something?