  We discuss the physics of D-branes and D-brane instantons intersecting at
angles, focusing on the (non)generation of a superpotential in the worldvolume
theory of the branes. This is a short review of the results in arXiv:0905.1694,
where we further emphasize both the macroscopic and microscopic structure of
the manifestly supersymmetric instanton action. We also comment on the lift of
O(1) instantons to F-theory.
