This might be a weird edge case, but in Rust, 0MQ bindings came really quickly, as its protocol was easy. This let Rust do web stuff _far_ earlier than the still-ongoing work to actually write a server in Rust itself.

At least in Ruby world, we steal Mongrel's parser over and over and over and over. Seems like it might be easier to not have to do that, and just use Mongrel2 with a 0MQ library. I haven't actually done this, though...