For few other approaches implemented for WebGL see here:

http://0fps.net/2012/07/12/smooth-voxel-terrain-part-2/

Marching cubes is 3d isosurface reconstruction, and recently it has become un-patent encumbered, so there's a new rennaisance of usage.

From my google searches, all I can find on "Marching tiles" is a bunch of 2d stuff. Hardly state of the art...

Can you direct me to what you meant when you said state of the art?