At Scrapinghub we have been using mesos to run our core services in production for one year. Mesos is awesome and we really love it! We'd like to add our organization to the "Powered By Mesos" page.
I've created a RB patch here: https://reviews.apache.org/r/37513/
Scrapinghub is the leading platform for deploying, running and scaling web crawlers. We've redesigned large part of our Paas based on mesos, and we plan to open source part of it in the future!
Shuai (+ Scrapinghub's Scrapy Cloud team)