A: 

I once built something very similar, but as a small, REST app (in TurboGears).

Never quite got the performance and reliability up to where I could use it for anything serious. And it was designed before webhooks started to take root, so I'd probably take that into consideration now.

As I'm also working in Django now, I'll be curious to see what you come up with. I think your design is about right, and this kind of event dispatcher is very useful and worth working on.

thraxil
+1  A: 

django-notification by James Tauber gets you a good chunk of the way there. I would love to see that app mature if you're willing to work off of that codebase it would be great.

Adam Nelson
A: 

Isn't this a case for pub/sub? Maybe something like that

DeeJay1