In the past several years, there has been a tremendous amount of attention paid to invariants called Heegaard Floer homology groups. These groups have proven useful in a number of applications in 3- and 4-dimensional topology. In this talk, I'll define and discuss a brand-new invariant of Legendrian and transverse knots which lives in the Heegaard Floer homology of the ambient space. This invariant enjoys many interesting and useful properties. Most notably, the invariant is capable of distinguishing certain knots in overtwisted contact 3-manifolds.