Well, this isn't Skritter in the sense of practising, but the panel and recognition are very similar. And it uses HTML5 -- not a similarity but rather something where collaboration might be worthwhile.
I know there is a high proportion of "scientifically inclined" users on Skritter (including the founders), perhaps you're interested. A Wacom makes the tool even more exciting.
http://detexify.kirelabs.org