>After each batch of new data was received from the AP, this server determined which pages needed to be re-rendered and, using the Typhoeus libcurl-multi bindings for Ruby, pulled new data for each of these pages from the render pool.

Sounds like their infrastructure already has a farm of servers set up to handle rendering articles into their HTML components, so for this scenario they would save the output as a static file and then write it to disk rather than sending the HTML out to the response / caching layer / etc.