  We present a brief overview of some key concepts in the theory of generalised
complex manifolds. This new geometry interpolates, so to speak, between
symplectic geometry and complex geometry. As such it provides an ideal
framework to analyse thermodynamical fluctuation theory in the presence of
gravitational fields. To illustrate the usefulness of generalised complex
geometry, we examine a simplified version of the Unruh effect: the thermalising
effect of gravitational fields on the Schroedinger wavefunction.
