There has been some work on this. Apple's Pages uses an implementation of the Hobby spline, demonstrating that it can be used in real consumer products. I think if you put these two side-by-side though, mine comes out quite a bit better; when you push the Hobby spline you get curvature extrema quite a distance from the control points, and mine doesn't do that.
Hobby's work has of course been an inspiration for mine for a long time, and it holds up academically quite well too - it has just the right blend of practical and aesthetic considerations and theoretical analysis; his solver runs in linear time and there's a proof it always converges (as long as tension values are within a reasonable range).
And of course there's the k-Curve work from Adobe. I think it is a step forward from Hobby in some ways (more robust) but a step back in others (it's not as smooth and most especially doesn't form true inflections).
I'm curious, because I haven't seen much work built on top of Knuth and Hobby's "Most Pleasing Curve" as defined by Mathematical Typography [0] and Hobby's follow-up papers [1] [2] [3]. Has anybody investigated these? As far as I know they're just not very convenient to rasterize.
[0] http://www.math.lsa.umich.edu/~millerpd/docs/501_Winter13/Kn... [1] http://i.stanford.edu/pub/cstr/reports/cs/tr/85/1047/CS-TR-8... [2] http://ect.bell-labs.com/who/hobby/thesis.pdf [3] http://ect.bell-labs.com/who/hobby/87_2-04.pdf