Looks like this was done in Raphael from scratch. The history panel is very cool.

I have my own HTML 5 vector graphics editor http://editor.method.ac which is based off SVG Edit, so I understand the amount of work gone into this, it must have been an interesting challenge!

I small UX suggestion for your landing page: instead of warning people that they don't have save functionality unless they sign up first, allow your users to save their work by signing up. I'm sure a "Save and Sign Up" button would do wonders for your conversion rates.