Recent developments in four-dimensional supergravity

I will summarize recent work on gauge theories in supergravity, specifically concerning the `Fayet-Iliopoulos' parameter. In rigidly supersymmetric gauge theories, this parameter also appears and can vary continuously. In supergravity old lore held that it should always vanish. I will discuss recent developments showing that in fact it can be nonzero, but is quantized, and will explore various ramifications of that result.