http://code.google.com/p/glyphy/
The main difference between GLyphy and other SDF-based OpenGL renderers is that most other projects sample the SDF into a texture. This has all the usual problems that sampling has. Ie. it distorts the outline and is low quality. GLyphy instead represents the SDF using actual vectors submitted to the GPU. This results in very high quality rendering.
The downside is that the code is for iOS with OpenGL ES. I'm probably going to make a Windows/Linux OpenGL 4.x port (hopefully the author will add some real documentation, though).
