I will discuss a certain categorification of Kontsevich's virtual fundamental class, which I call derived microlocalization. Based on joint work with Tasuki Kinjo, I will explain how this formalism can be used to prove a conjecture of D. Joyce about categorified Donaldson-Thomas theory of Calabi-Yau threefolds. This has several consequences, including the existence of cohomological Hall algebras à la Kontsevich-Soibelman for Calabi-Yau threefolds.