McCann's displacement convexity means the convexity in the space of probability measures equipped with the Wasserstein distance. The displacement convexity of entropy (or free energy) plays an interesting role in various fields (including PDE, probability theory, Riemannian geometry). I will talk about its geometric aspect related to lower Ricci curvature bounds.
Links:
[1] http://www.mpim-bonn.mpg.de/de/taxonomy/term/39
[2] http://www.mpim-bonn.mpg.de/de/node/3444
[3] http://www.mpim-bonn.mpg.de/de/node/158