Anyone familiar with Bitcoin is likely aware of the 51% attack. A blog post is hardly warranted, because this isn't significant. GHash.io does not control all of that compute power. It is a metalayer that coordinates distinct and unrelated compute resources controlled by (supposedly) 180,000 seperate entities[0]. In order for a 50% attack to take place the vast majority (at this point) would have to agree to attack, and that simply won't happen.
[0] GHash.io homepage