We tested using Ubuntu 10.04, which comes prepackaged with MonoDevelop 2.2 and Mono 2.4.4. Our code builds cleanly with no warnings, and, thankfully, all of our unit tests pass:
(Yes, we actually write unit tests for the book code.) We need to investigate our examples that use a third party Shapefile reader a bit more, but we may wind up writing our own Shapefile reader when the manuscript is done.
I have to say that I am quite impressed with Mono, MonoDevelop, OpenTK, and NVIDIA's Linux drivers. Porting to Linux was even easier than I hoped.
We also plan to test on Mac when Apple releases OpenGL 3.3 drivers.