The OpenTK.OpenGL.Glu has been updated with preliminary tesselation support. Anyone interested, please download the attached zip and test it (the source is availble through SVN) and try using the code. A small example will be added to the OpenTK manual soon.
I am afraid that without feedback, no further updates will be done to this code. I strongly recommend to avoid using the GLU tesselation functions and prefer a managed triangulation solution instead.
As always, you may check progress in the Roadmap section and join our development discussions on on IRC (de.quakenet.org:6669, #opentk).
Update 1: OpenTK.OpenGL.Glu now works correctly. For now, only low-level access is provided to the tessellator functions (which may require the use of pointers in some cases). If you wish to help develop a safe managed wrapper over these functions, please make a post.