A $\Delta$-space is a Tychonoff space with the property that every partition of the space (into arbitrary sets) has a point finite open expansion. M. Reed defined a set of reals with this property to be a $\Delta$-set and was motivated by the characterization of a $\Delta$-set as those sets of reals $X$ for which the Moore plane over $X$ is countably paracompact. Recently, Leiderman and Kąkol characterized $\Delta$-spaces as those $X$ for which the locally convex space $C_p(X)$ is distinguished. I will survey some recent results concerning $\Delta$-spaces and mention a number of open problems.