According to the blog[1], it's Rackspace. [1]: http://journal.sifterapp.com/blog/2011/08/sifters-new-hosting/ http://journal.sifterapp.com/blog/2011/08/sifters

According to the blog[1], it's Rackspace. [1]: http://journal.sifterapp.com/blog/2011/08/sifters-new-hosting/ http://journal.sifterapp.com/blog/2011/08/sifters-new-hostin...