http://alistapart.com/article/live-font-interpolation-on-the-web calls for a discussion in this forum about 'live' interpolation of web fonts, and a demo is provided at
http://aetherpoint.com/lab/interpolation/ I'm very happy to see this idea get wider circulation, and that the demo uses similar technology as the demo the metapolator community developed at
http://metapolator.com/index_old.html last year; also the www.prototypo.io developers have made
http://byte-foundry.github.io/plumin.js/ which seems to have long term potential

Looking forward to Nick's article out on Friday - click through to twitter to see the replies including Adam Twardoch's reminder about
http://lists.w3.org/Archives/Public/public-webfonts-wg/2013Jun/0024.html
Comments
Compression is best solved elsewhere, I think, so, maybe the tech companies will be disappointed in just better lookin stuff. In fact, I'm really curious if this will happen, from the type industry, just for 'faster', and not for 'prettier.'
For the handful of designers who would use this properly, there will be 10 more who won't. (Possibly and not excluding me.)
Isn't that what computers are for?
I just have no faith that I won't want to gauge my eyes out in the uncertain future.
http://alistapart.com/blog/post/variable-fonts-for-responsive-design
At the end he writes,
I think that often responses to this topic are that the type community must rely on web browser developers to do something, much like relying on desktop software developers to do something in the past; for example looking back to the MultipleMasters and TrueTypeGX formats from the 90s and suggesting they be revitalized.
However, I think that as Andrew's proof of concept shows, we don't need to wait for browser developers - their vision can be realised purely in JavaScript, if someone extends http://nodebox.github.io/opentype.js/ to take as input 2 interpolatable fonts and output a working instance. As noted in the articles, this would be better for CFF than TTF.
On twitter, Kris Sowersby asked,
and Nick replied,
I think we can already see that the speculative table comparing 6 singleton fonts vs 4 interpolation-master fonts has promise, from http://byte-foundry.github.io/plumin.js/
Plumin.js is a friendly API around opentype.js, and http://byte-foundry.github.io/plumin.js/bugreport.html shows an animation example running in Chrome bug free (the page is a bug report for Firefox
The appearance of animation on this page is an illusion; in fact each frame of the animation is a new font being generated and loaded and rendered by the browser. Well, the font has just 3 simple glyphs, but this seems promising to me.
If an opentype.js based interpolator is written, then the proof of demand for what Nick and Andrew have expertly explained can be shown with JavaScript. If it proves untenably slow in JS, browser developers would see the proof of utility and someday implement support for similar technology natively... but I'm optimistic that JS will be fast enough.