Definitely. I have seen at least couple other firefox extensions to do the same thing (here's one: http://www.yakalike.com/). I was involved in a drawing/graffiti type one last year (http://drawhere.com). It was fun to try and get done in javascript, but it was hard to hold people's interest for an extended period. There's a history of this stuff failing: http://wired-vig.wired.com/news/business/0,1367,42803-2,00.html

I'll be curious to see if/how someone gets it to stick.