The big problem with this spec (which is shared today by all the HTTP uploads in the world) is that you have to check for the delimiter every byte!

"Content-Type: chunked" is much better because it gives you the size of each chunk upfront! But that requires .js and also was buggy in IE until version 7.

I made a multiplayer online system that relies on chunked: https://github.com/tinspin/fuse