Hi,
I've implemented some auto-smoothing algorithms for mesh gradients in trunk. It would be very helpful others can have a look a it. Normal Coons Patch mesh gradients suffer from abrupt changes in the color derivatives along patch boundaries which leads to undesirable visible artifacts (Mach Banding). Both Illustrator and CoralDraw implement smoothing to eliminate this problem. I will be proposing to the SVG working group that SVG 2 mesh gradients should have an auto-smoothing option.
I've turned on some experimental features in trunk including meshes. Information on how to edit meshes and what smoothing options are implemented can be found at:
http://wiki.inkscape.org/wiki/index.php/Mesh_Gradients
Most of the derivative calculations are currently being done using a "Catmul-Rom" method which assumes an evenly spaced grid. I'll change this to allow for un-even grids in the near future.
Thanks,
Tav