It's funny to see this pop up now. I'm writing a demo (one shader for two triangles) that does 2d distance field rendering, and I'm using quadratic bezier curves for a large part of it. Rather than an optimized form, I'm just iterating over the curve and then doing a point-line distance calculation for each step; it's not the most efficient way to do it, but it's plenty fast on modern GPUs.

I'm excited to see where accelerated path rendering goes in the future. In conjunction with distance field rendering, it's absolutely fantastic.