How is this different than NowJS (http://nowjs.com/)? I don't mean to imply that two similar modules cannot exist; I am just curious if there is some fundamental difference between the two or if Racer is just a project that isn't as far along.
Racer is real-time model synchronisation.
Fundamentally they are completely different. They happen to use similar technology stacks and both contain the word 'realtime' but they are completely different projects. They actually might work quite well as compliments to each other.