Magmatism and coupled fluid-solid mechanics are essential processes governing the dynamics of plate boundaries and are critical for relating observable geochemistry to geodynamics. We review the basic formulation for fluid flow in viscously deformable permeable media and demonstrate that it is a straightforward coupling of Mantle convection and fluid flow in porous media. However, the behavior of the coupled system is considerably richer than either sub-problem alone. We illustrate this behavior it through a series of model problems and associated observations that suggest that magmatism in the mantle is inherently time-dependent and may lead to localization into some form of channelized melt network. This behavior presents considerable computational challenges for developing community software for exploring coupled mantle/magma dynamics (e.g. through the Computational Infrastructure for Geodynamics, CIG) and we will discuss current progress on this front.